diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -5,9 +5,16 @@
 ## Unreleased changes
 
 
+## Version 0.7.0.1
+
+-   Random 1.2: Parallel functions now require an \`IOGenM\` random number
+    generator.
+-   Fix splitting of the random number generator.
+
+
 ## Version 0.6.1.1
 
--   Remove plotting functionality (gnuplot incompatible with ghc921).
+-   Remove plotting functionality (gnuplot incompatible with ghc922).
 -   Read files strictly.
 -   Refactor; flatten model hierarchy.
 
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -2,7 +2,7 @@
 
 # The ELynx Suite
 
-Version: 0.6.1.1.
+Version: 0.7.0.0.
 Reproducible evolution made easy.
 
 <p align="center"><img src="https://travis-ci.org/dschrempf/elynx.svg?branch=master"/></p>
@@ -74,9 +74,9 @@
     # OR: slynx --help
 
     Up to date
-    ELynx Suite version 0.6.1.1.
+    ELynx Suite version 0.7.0.0.
     Developed by Dominik Schrempf.
-    Compiled on February 22, 2022, at 15:10 pm, UTC.
+    Compiled on July 10, 2022, at 08:48 am, UTC.
     
     Usage: slynx [-v|--verbosity VALUE] [-o|--output-file-basename NAME]
                  [-f|--force] [--no-elynx-file] COMMAND
@@ -144,16 +144,16 @@
     # OR: slynx simulate --help
 
     Up to date
-    ELynx Suite version 0.6.1.1.
+    ELynx Suite version 0.7.0.0.
     Developed by Dominik Schrempf.
-    Compiled on February 22, 2022, at 15:10 pm, UTC.
+    Compiled on July 10, 2022, at 08:48 am, UTC.
     
     Usage: slynx simulate (-t|--tree-file Name) [-s|--substitution-model MODEL]
                           [-m|--mixture-model MODEL] [-e|--edm-file NAME]
                           [-p|--siteprofile-files NAMES]
                           [-w|--mixture-model-weights "[DOUBLE,DOUBLE,...]"]
                           [-g|--gamma-rate-heterogeneity "(NCAT,SHAPE)"]
-                          (-l|--length NUMBER) [-S|--seed [INT]]
+                          (-l|--length NUMBER) [-S|--seed INT]
       Simulate multi sequence alignments.
     
     Available options:
@@ -175,8 +175,7 @@
       -g,--gamma-rate-heterogeneity "(NCAT,SHAPE)"
                                Number of gamma rate categories and shape parameter
       -l,--length NUMBER       Set alignment length to NUMBER
-      -S,--seed [INT]          Seed for random number generator; list of 32 bit
-                               integers with up to 256 elements (default: random)
+      -S,--seed INT            Seed for random number generator (default: random)
       -h,--help                Show this help text
     
     Substitution models:
diff --git a/bench/Bench.hs b/bench/Bench.hs
--- a/bench/Bench.hs
+++ b/bench/Bench.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  Bench
 -- Description :  Various benchmarks
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -22,7 +22,7 @@
 import ELynx.Tree.Simulate.PointProcess
 import Length
 import Lens
-import System.Random.MWC
+import System.Random.Stateful
 import Tree
 
 treeFileMany :: FilePath
@@ -32,7 +32,7 @@
 getManyTrees = parseFileWith (someNewick Standard) treeFileMany
 
 hugeTree :: IO (Tree Length Int)
-hugeTree = create >>= simulateReconstructedTree 50000 Random 1.0 0.9
+hugeTree = newIOGenM (mkStdGen 0) >>= simulateReconstructedTree 50000 Random 1.0 0.9
 
 sinN :: Int -> Length -> Length
 sinN n x = iterate sin x !! n
diff --git a/bench/Length.hs b/bench/Length.hs
--- a/bench/Length.hs
+++ b/bench/Length.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  Length
 -- Description :  Benchmark length newtype
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/bench/Lens.hs b/bench/Lens.hs
--- a/bench/Lens.hs
+++ b/bench/Lens.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  Lens
 -- Description :  Benchmark lens operations
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/bench/Tree.hs b/bench/Tree.hs
--- a/bench/Tree.hs
+++ b/bench/Tree.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  Tree
 -- Description :  Benchmark some tree algorithms
--- Copyright   :  (c) 2021 Dominik Schrempf
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/elynx-tree.cabal b/elynx-tree.cabal
--- a/elynx-tree.cabal
+++ b/elynx-tree.cabal
@@ -1,81 +1,82 @@
-cabal-version:  3.0
-name:           elynx-tree
-version:        0.6.1.1
-synopsis:       Handle phylogenetic trees
-description:    Examine, compare, and simulate phylogenetic trees in a reproducible way. Please see the README on GitHub at <https://github.com/dschrempf/elynx>.
-category:       Bioinformatics
-homepage:       https://github.com/dschrempf/elynx#readme
-bug-reports:    https://github.com/dschrempf/elynx/issues
-author:         Dominik Schrempf
-maintainer:     dominik.schrempf@gmail.com
-copyright:      Dominik Schrempf (2021)
-license:        GPL-3.0-or-later
-license-file:   LICENSE
-build-type:     Simple
+cabal-version:      3.0
+name:               elynx-tree
+version:            0.7.0.1
+synopsis:           Handle phylogenetic trees
+description:
+  Examine, compare, and simulate phylogenetic trees in a reproducible way. Please see the README on GitHub at <https://github.com/dschrempf/elynx>.
 
+category:           Bioinformatics
+homepage:           https://github.com/dschrempf/elynx#readme
+bug-reports:        https://github.com/dschrempf/elynx/issues
+author:             Dominik Schrempf
+maintainer:         dominik.schrempf@gmail.com
+copyright:          2021 Dominik Schrempf
+license:            GPL-3.0-or-later
+license-file:       LICENSE
+build-type:         Simple
 extra-source-files:
-    README.md
-    ChangeLog.md
-    data/ConnectA.tree
-    data/ConnectB.tree
-    data/ConnectConstraints.tree
-    data/Many.trees
-    data/MicrospoEDM32.tree
-    data/MicrospoEDM64.tree
-    data/MicrospoPoisson.tree
-    data/Multifurcating.tree
-    data/NewickConstraint.tree
-    data/NewickRevBayes.tree
-    data/NewickRooted.tree
-    data/Newick.tree
-    data/RevBayes.trees
-    data/SimpleTree.nex
-    data/TreeDist.trees
-    data/UltraMetric.tree
+  ChangeLog.md
+  data/ConnectA.tree
+  data/ConnectB.tree
+  data/ConnectConstraints.tree
+  data/Many.trees
+  data/MicrospoEDM32.tree
+  data/MicrospoEDM64.tree
+  data/MicrospoPoisson.tree
+  data/Multifurcating.tree
+  data/Newick.tree
+  data/NewickConstraint.tree
+  data/NewickRevBayes.tree
+  data/NewickRooted.tree
+  data/RevBayes.trees
+  data/SimpleTree.nex
+  data/TreeDist.trees
+  data/UltraMetric.tree
+  README.md
 
 source-repository head
-  type: git
+  type:     git
   location: https://github.com/dschrempf/elynx
 
 library
   exposed-modules:
-      ELynx.Topology
-      ELynx.Topology.Phylogeny
-      ELynx.Topology.Rooted
-      ELynx.Tree
-      ELynx.Tree.Bipartition
-      ELynx.Tree.Distance
-      ELynx.Tree.Length
-      ELynx.Tree.Name
-      ELynx.Tree.Parallel
-      ELynx.Tree.Partition
-      ELynx.Tree.Phylogeny
-      ELynx.Tree.Rooted
-      ELynx.Tree.Splittable
-      ELynx.Tree.Support
-      ELynx.Tree.Zipper
-      ELynx.Tree.Distribution.BirthDeath
-      ELynx.Tree.Distribution.BirthDeathCritical
-      ELynx.Tree.Distribution.BirthDeathCriticalNoTime
-      ELynx.Tree.Distribution.BirthDeathNearlyCritical
-      ELynx.Tree.Distribution.CoalescentContinuous
-      ELynx.Tree.Distribution.TimeOfOrigin
-      ELynx.Tree.Distribution.TimeOfOriginNearCritical
-      ELynx.Tree.Distribution.Types
-      ELynx.Tree.Export.Newick
-      ELynx.Tree.Export.Nexus
-      ELynx.Tree.Import.Newick
-      ELynx.Tree.Import.Nexus
-      ELynx.Tree.Simulate.Coalescent
-      ELynx.Tree.Simulate.PointProcess
-  other-modules:
-      Paths_elynx_tree
-  autogen-modules:
-      Paths_elynx_tree
-  hs-source-dirs: src
-  ghc-options: -Wall -Wunused-packages
+    ELynx.Topology
+    ELynx.Topology.Phylogeny
+    ELynx.Topology.Rooted
+    ELynx.Tree
+    ELynx.Tree.Bipartition
+    ELynx.Tree.Distance
+    ELynx.Tree.Distribution.BirthDeath
+    ELynx.Tree.Distribution.BirthDeathCritical
+    ELynx.Tree.Distribution.BirthDeathCriticalNoTime
+    ELynx.Tree.Distribution.BirthDeathNearlyCritical
+    ELynx.Tree.Distribution.CoalescentContinuous
+    ELynx.Tree.Distribution.TimeOfOrigin
+    ELynx.Tree.Distribution.TimeOfOriginNearCritical
+    ELynx.Tree.Distribution.Types
+    ELynx.Tree.Export.Newick
+    ELynx.Tree.Export.Nexus
+    ELynx.Tree.Import.Newick
+    ELynx.Tree.Import.Nexus
+    ELynx.Tree.Length
+    ELynx.Tree.Mrca
+    ELynx.Tree.Name
+    ELynx.Tree.Parallel
+    ELynx.Tree.Partition
+    ELynx.Tree.Phylogeny
+    ELynx.Tree.Rooted
+    ELynx.Tree.Simulate.Coalescent
+    ELynx.Tree.Simulate.PointProcess
+    ELynx.Tree.Splittable
+    ELynx.Tree.Support
+    ELynx.Tree.Zipper
+
+  other-modules:    Paths_elynx_tree
+  autogen-modules:  Paths_elynx_tree
+  hs-source-dirs:   src
+  ghc-options:      -Wall -Wunused-packages
   build-depends:
-      aeson
+    , aeson
     , attoparsec
     , base
     , bytestring
@@ -86,37 +87,39 @@
     , double-conversion
     , elynx-nexus
     , math-functions
-    , mwc-random
     , parallel
-    , primitive
+    , random
     , statistics
+
   default-language: Haskell2010
 
 test-suite tree-test
-  type: exitcode-stdio-1.0
-  main-is: Spec.hs
+  type:             exitcode-stdio-1.0
+  main-is:          Spec.hs
   other-modules:
-      ELynx.ClassLaws
-      ELynx.Topology.Arbitrary
-      ELynx.Topology.RootedSpec
-      ELynx.Tree.Arbitrary
-      ELynx.Tree.BipartitionSpec
-      ELynx.Tree.DistanceSpec
-      ELynx.Tree.PartitionSpec
-      ELynx.Tree.PhylogenySpec
-      ELynx.Tree.RootedSpec
-      ELynx.Tree.SupportSpec
-      ELynx.Tree.Export.NewickSpec
-      ELynx.Tree.Export.NexusSpec
-      ELynx.Tree.Import.NewickSpec
-      ELynx.Tree.Import.NexusSpec
-      Paths_elynx_tree
-  autogen-modules:
-      Paths_elynx_tree
-  hs-source-dirs: test
-  ghc-options: -Wall -Wunused-packages -threaded -rtsopts -with-rtsopts=-N
+    ELynx.ClassLaws
+    ELynx.Topology.Arbitrary
+    ELynx.Topology.RootedSpec
+    ELynx.Tree.Arbitrary
+    ELynx.Tree.BipartitionSpec
+    ELynx.Tree.DistanceSpec
+    ELynx.Tree.Export.NewickSpec
+    ELynx.Tree.Export.NexusSpec
+    ELynx.Tree.Import.NewickSpec
+    ELynx.Tree.Import.NexusSpec
+    ELynx.Tree.PartitionSpec
+    ELynx.Tree.PhylogenySpec
+    ELynx.Tree.RootedSpec
+    ELynx.Tree.SupportSpec
+    Paths_elynx_tree
+
+  autogen-modules:  Paths_elynx_tree
+  hs-source-dirs:   test
+  ghc-options:
+    -Wall -Wunused-packages -threaded -rtsopts -with-rtsopts=-N
+
   build-depends:
-      attoparsec
+    , attoparsec
     , base
     , bytestring
     , containers
@@ -126,26 +129,30 @@
     , hspec
     , QuickCheck
     , quickcheck-classes
+
   default-language: Haskell2010
 
 benchmark tree-bench
-  type: exitcode-stdio-1.0
-  main-is: Bench.hs
+  type:             exitcode-stdio-1.0
+  main-is:          Bench.hs
   other-modules:
-      Length
-      Lens
-      Tree
-      Paths_elynx_tree
-  autogen-modules:
-      Paths_elynx_tree
-  hs-source-dirs: bench
-  ghc-options: -Wall -Wunused-packages -threaded -rtsopts -with-rtsopts=-N
+    Length
+    Lens
+    Paths_elynx_tree
+    Tree
+
+  autogen-modules:  Paths_elynx_tree
+  hs-source-dirs:   bench
+  ghc-options:
+    -Wall -Wunused-packages -threaded -rtsopts -with-rtsopts=-N
+
   build-depends:
-      base >=4.7 && <5
+    , base         >=4.7 && <5
     , criterion
     , elynx-tools
     , elynx-tree
     , microlens
-    , mwc-random
     , parallel
+    , random
+
   default-language: Haskell2010
diff --git a/src/ELynx/Topology.hs b/src/ELynx/Topology.hs
--- a/src/ELynx/Topology.hs
+++ b/src/ELynx/Topology.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Topology
 -- Description :  Rooted topologies
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Topology/Phylogeny.hs b/src/ELynx/Topology/Phylogeny.hs
--- a/src/ELynx/Topology/Phylogeny.hs
+++ b/src/ELynx/Topology/Phylogeny.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Topology.Phylogeny
 -- Description :  Phylogenetic topologies
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -66,8 +66,8 @@
 intersect ts
   | S.null lvsCommon = Left "intersect: Intersection of leaves is empty."
   | otherwise = case sequence [dropLeavesWith (predicate ls) t | (ls, t) <- zip leavesToDrop ts] of
-    Nothing -> Left "intersect: A topology is empty."
-    Just ts' -> Right ts'
+      Nothing -> Left "intersect: A topology is empty."
+      Just ts' -> Right ts'
   where
     -- Leaf sets.
     lvss = map (S.fromList . leaves) ts
diff --git a/src/ELynx/Topology/Rooted.hs b/src/ELynx/Topology/Rooted.hs
--- a/src/ELynx/Topology/Rooted.hs
+++ b/src/ELynx/Topology/Rooted.hs
@@ -4,7 +4,7 @@
 -- |
 -- Module      :  ELynx.Topology.Rooted
 -- Description :  Topologies
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree.hs b/src/ELynx/Tree.hs
--- a/src/ELynx/Tree.hs
+++ b/src/ELynx/Tree.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree
 -- Description :  Rooted trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -32,6 +32,9 @@
     -- * Phylogenies
     module ELynx.Tree.Phylogeny,
 
+    -- * Most recent common ancestors
+    module ELynx.Tree.Mrca,
+
     -- * Partitions and distances
     module ELynx.Tree.Bipartition,
     module ELynx.Tree.Partition,
@@ -52,6 +55,7 @@
 import ELynx.Tree.Import.Newick
 import ELynx.Tree.Import.Nexus
 import ELynx.Tree.Length
+import ELynx.Tree.Mrca
 import ELynx.Tree.Name
 import ELynx.Tree.Parallel
 import ELynx.Tree.Partition
diff --git a/src/ELynx/Tree/Bipartition.hs b/src/ELynx/Tree/Bipartition.hs
--- a/src/ELynx/Tree/Bipartition.hs
+++ b/src/ELynx/Tree/Bipartition.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Bipartition
 -- Description :  Bipartitions on trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -146,7 +146,7 @@
   [Set a]
 getComplementaryLeaves p (Node _ _ ts) =
   [ S.unions $ p : take i lvsChildren ++ drop (i + 1) lvsChildren
-    | i <- [0 .. (n -1)]
+    | i <- [0 .. (n - 1)]
   ]
   where
     n = length ts
@@ -158,8 +158,8 @@
 bipartitions' p (Node _ p' []) = either (const S.empty) S.singleton $ bp p p'
 bipartitions' p t@(Node _ p' ts) =
   S.unions $
-    either (const S.empty) S.singleton (bp p p') :
-      [bipartitions' c s | (c, s) <- zip cs ts]
+    either (const S.empty) S.singleton (bp p p')
+      : [bipartitions' c s | (c, s) <- zip cs ts]
   where
     cs = getComplementaryLeaves p t
 
@@ -200,7 +200,7 @@
   Map (Bipartition a) e
 bipartitionToBranch' p t@(Node b p' ts) =
   M.unionsWith (<>) $
-    either (const M.empty) (`M.singleton` b) (bp p p') :
-      [bipartitionToBranch' c s | (c, s) <- zip cs ts]
+    either (const M.empty) (`M.singleton` b) (bp p p')
+      : [bipartitionToBranch' c s | (c, s) <- zip cs ts]
   where
     cs = getComplementaryLeaves p t
diff --git a/src/ELynx/Tree/Distance.hs b/src/ELynx/Tree/Distance.hs
--- a/src/ELynx/Tree/Distance.hs
+++ b/src/ELynx/Tree/Distance.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Distance
 -- Description :  Compute distances between trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -55,11 +55,11 @@
 symmetric :: Ord a => Tree e1 a -> Tree e2 a -> Either String Int
 symmetric t1 t2
   | S.fromList (leaves t1) /= S.fromList (leaves t2) =
-    Left "symmetric: Trees contain different leaves."
+      Left "symmetric: Trees contain different leaves."
   | otherwise = do
-    bps1 <- bipartitions t1
-    bps2 <- bipartitions t2
-    return $ length $ symmetricDifference bps1 bps2
+      bps1 <- bipartitions t1
+      bps2 <- bipartitions t2
+      return $ length $ symmetricDifference bps1 bps2
 
 countIncompatibilities :: (Show a, Ord a) => Set (Bipartition a) -> Set (Partition a) -> Int
 countIncompatibilities bs ms =
@@ -102,22 +102,22 @@
 incompatibleSplits :: (Show a, Ord a) => Tree e1 a -> Tree e2 a -> Either String Int
 incompatibleSplits t1 t2
   | S.fromList (leaves t1) /= S.fromList (leaves t2) =
-    Left "incompatibleSplits: Trees contain different leaves."
+      Left "incompatibleSplits: Trees contain different leaves."
   | otherwise = do
-    -- Bipartitions.
-    bs1 <- bipartitions t1
-    bs2 <- bipartitions t2
-    -- traceShowM $ "bs1" ++ show (S.map bpHuman bs1)
-    -- traceShowM $ "bs2" ++ show (S.map bpHuman bs2)
-    let -- Putative incompatible bipartitions of trees one and two, respectively.
-        putIncBs1 = bs1 S.\\ bs2
-        putIncBs2 = bs2 S.\\ bs1
-    -- Partitions.
-    ms1 <- partitions t1
-    ms2 <- partitions t2
-    -- traceShowM $ "putIncBs1 " ++ show (S.map bpHuman putIncBs1)
-    -- traceShowM $ "putIncBs2 " ++ show (S.map bpHuman putIncBs2)
-    return $ countIncompatibilities putIncBs1 ms2 + countIncompatibilities putIncBs2 ms1
+      -- Bipartitions.
+      bs1 <- bipartitions t1
+      bs2 <- bipartitions t2
+      -- traceShowM $ "bs1" ++ show (S.map bpHuman bs1)
+      -- traceShowM $ "bs2" ++ show (S.map bpHuman bs2)
+      let -- Putative incompatible bipartitions of trees one and two, respectively.
+          putIncBs1 = bs1 S.\\ bs2
+          putIncBs2 = bs2 S.\\ bs1
+      -- Partitions.
+      ms1 <- partitions t1
+      ms2 <- partitions t2
+      -- traceShowM $ "putIncBs1 " ++ show (S.map bpHuman putIncBs1)
+      -- traceShowM $ "putIncBs2 " ++ show (S.map bpHuman putIncBs2)
+      return $ countIncompatibilities putIncBs1 ms2 + countIncompatibilities putIncBs2 ms1
 
 -- | Compute branch score distance between two trees.
 --
@@ -128,10 +128,10 @@
 branchScore :: (HasLength e1, HasLength e2, Ord a) => Tree e1 a -> Tree e2 a -> Either String Double
 branchScore t1 t2
   | S.fromList (leaves t1) /= S.fromList (leaves t2) =
-    Left "branchScoreWith: Trees contain different leaves."
+      Left "branchScoreWith: Trees contain different leaves."
   | otherwise = do
-    bpToBr1 <- bipartitionToBranch $ first (Sum . getLength) t1
-    bpToBr2 <- bipartitionToBranch $ first (Sum . getLength) t2
-    let dBs = M.unionWith (-) bpToBr1 bpToBr2
-        dsSquared = foldl' (\acc e -> acc + e * e) 0 dBs
-    return $ sqrt $ fromLength $ getSum dsSquared
+      bpToBr1 <- bipartitionToBranch $ first (Sum . getLength) t1
+      bpToBr2 <- bipartitionToBranch $ first (Sum . getLength) t2
+      let dBs = M.unionWith (-) bpToBr1 bpToBr2
+          dsSquared = foldl' (\acc e -> acc + e * e) 0 dBs
+      return $ sqrt $ fromLength $ getSum dsSquared
diff --git a/src/ELynx/Tree/Distribution/BirthDeath.hs b/src/ELynx/Tree/Distribution/BirthDeath.hs
--- a/src/ELynx/Tree/Distribution/BirthDeath.hs
+++ b/src/ELynx/Tree/Distribution/BirthDeath.hs
@@ -4,7 +4,7 @@
 -- |
 --   Module      :  ELynx.Tree.Distribution.BirthDeath
 --   Description :  Birth and death distribution
---   Copyright   :  (c) Dominik Schrempf 2021
+--   Copyright   :  2021 Dominik Schrempf
 --   License     :  GPL-3.0-or-later
 --
 --   Maintainer  :  dominik.schrempf@gmail.com
@@ -57,8 +57,8 @@
   | otherwise = t1 * t2
   where
     d = l - m
-    t1 = (1.0 - exp (- d * x)) / (l - m * exp (- d * x))
-    t2 = (l - m * exp (- d * t)) / (1.0 - exp (- d * t))
+    t1 = (1.0 - exp (-d * x)) / (l - m * exp (-d * x))
+    t2 = (l - m * exp (-d * t)) / (1.0 - exp (-d * t))
 
 instance D.ContDistr BirthDeathDistribution where
   density = density
@@ -72,23 +72,23 @@
   | otherwise = d ** 2 * t1 * t2
   where
     d = l - m
-    t1 = exp (- d * x) / ((l - m * exp (- d * x)) ** 2)
-    t2 = (l - m * exp (- d * t)) / (1.0 - exp (- d * t))
+    t1 = exp (-d * x) / ((l - m * exp (-d * x)) ** 2)
+    t2 = (l - m * exp (-d * t)) / (1.0 - exp (-d * t))
 
 -- | Inverted cumulative probability distribution 'cumulative'. See also
 -- 'D.ContDistr'.
 quantile :: BirthDeathDistribution -> Double -> Time
 quantile (BDD t l m) p
   | p >= 0 && p <= 1 =
-    res
+      res
   | otherwise =
-    error $
-      "BirthDeath.quantile: p must be in range [0,1] but got "
-        ++ show p
-        ++ "."
+      error $
+        "BirthDeath.quantile: p must be in range [0,1] but got "
+          ++ show p
+          ++ "."
   where
     d = l - m
-    t2 = (l - m * exp (- d * t)) / (1.0 - exp (- d * t))
+    t2 = (l - m * exp (-d * t)) / (1.0 - exp (-d * t))
     res = (-1.0 / d) * log ((1.0 - p * l / t2) / (1.0 - p * m / t2))
 
 instance D.ContGen BirthDeathDistribution where
diff --git a/src/ELynx/Tree/Distribution/BirthDeathCritical.hs b/src/ELynx/Tree/Distribution/BirthDeathCritical.hs
--- a/src/ELynx/Tree/Distribution/BirthDeathCritical.hs
+++ b/src/ELynx/Tree/Distribution/BirthDeathCritical.hs
@@ -4,7 +4,7 @@
 -- |
 --   Module      :  ELynx.Tree.Distribution.BirthDeathCritical
 --   Description :  Birth and death distribution
---   Copyright   :  (c) Dominik Schrempf 2021
+--   Copyright   :  2021 Dominik Schrempf
 --   License     :  GPL-3.0-or-later
 --
 --   Maintainer  :  dominik.schrempf@gmail.com
@@ -71,12 +71,12 @@
 quantile :: BirthDeathCriticalDistribution -> Double -> Time
 quantile (BDCD t l) p
   | p >= 0 && p <= 1 =
-    res
+      res
   | otherwise =
-    error $
-      "PointProcess.quantile: p must be in [0,1] range. Got: "
-        ++ show p
-        ++ "."
+      error $
+        "PointProcess.quantile: p must be in [0,1] range. Got: "
+          ++ show p
+          ++ "."
   where
     res = p * t / (1 + l * t - l * p * t)
 
diff --git a/src/ELynx/Tree/Distribution/BirthDeathCriticalNoTime.hs b/src/ELynx/Tree/Distribution/BirthDeathCriticalNoTime.hs
--- a/src/ELynx/Tree/Distribution/BirthDeathCriticalNoTime.hs
+++ b/src/ELynx/Tree/Distribution/BirthDeathCriticalNoTime.hs
@@ -4,7 +4,7 @@
 -- |
 --   Module      :  ELynx.Tree.Distribution.BirthDeathCriticalNoTime
 --   Description :  Birth and death distribution
---   Copyright   :  (c) Dominik Schrempf 2021
+--   Copyright   :  2021 Dominik Schrempf
 --   License     :  GPL-3.0-or-later
 --
 --   Maintainer  :  dominik.schrempf@gmail.com
@@ -68,9 +68,9 @@
 quantile :: BirthDeathCriticalNoTimeDistribution -> Double -> Time
 quantile (BDCNTD l) p
   | p >= 0 && p <= 1 =
-    p / (l - l * p)
+      p / (l - l * p)
   | otherwise =
-    error $ "PointProcess.quantile: p must be in [0,1]. Got: " ++ show p ++ "."
+      error $ "PointProcess.quantile: p must be in [0,1]. Got: " ++ show p ++ "."
 
 instance D.ContGen BirthDeathCriticalNoTimeDistribution where
   genContVar = D.genContinuous
diff --git a/src/ELynx/Tree/Distribution/BirthDeathNearlyCritical.hs b/src/ELynx/Tree/Distribution/BirthDeathNearlyCritical.hs
--- a/src/ELynx/Tree/Distribution/BirthDeathNearlyCritical.hs
+++ b/src/ELynx/Tree/Distribution/BirthDeathNearlyCritical.hs
@@ -4,7 +4,7 @@
 -- |
 --   Module      :  ELynx.Tree.Distribution.BirthDeathNearlyCritical
 --   Description :  Birth and death distribution
---   Copyright   :  (c) Dominik Schrempf 2021
+--   Copyright   :  2021 Dominik Schrempf
 --   License     :  GPL-3.0-or-later
 --
 --   Maintainer  :  dominik.schrempf@gmail.com
@@ -60,7 +60,7 @@
   | otherwise = o0 + o1
   where
     o0 = s * (1.0 + t * l) / t / (1.0 + s * l)
-    o1 = (- s * s + s * t) * (m - l) / (2.0 * t * (1.0 + s * l) ** 2)
+    o1 = (-s * s + s * t) * (m - l) / (2.0 * t * (1.0 + s * l) ** 2)
 
 instance D.ContDistr BirthDeathNearlyCriticalDistribution where
   density = density
@@ -81,27 +81,27 @@
 quantile :: BirthDeathNearlyCriticalDistribution -> Double -> Time
 quantile (BDNCD t l m) p
   | p >= 0 && p <= 1 =
-    res
+      res
   | otherwise =
-    error $
-      "PointProcess.quantile: p must be in [0,1] range. Got: "
-        ++ show p
-        ++ "."
+      error $
+        "PointProcess.quantile: p must be in [0,1] range. Got: "
+          ++ show p
+          ++ "."
   where
     den = l * (-3.0 + 2.0 * t * (-1.0 + p) * l) + m
     t1 = (2.0 + t * (l - 4.0 * p * l + m)) / den
     t2Nom =
       4.0
         + t
-        * ( l
-              * (4.0 + t * l + 8.0 * p * (1.0 + t * l))
-              + 2.0
-              * (2.0 + t * l - 4.0 * p * (1.0 + t * l))
-              * m
-              + t
-              * m
-              * m
-          )
+          * ( l
+                * (4.0 + t * l + 8.0 * p * (1.0 + t * l))
+                + 2.0
+                  * (2.0 + t * l - 4.0 * p * (1.0 + t * l))
+                  * m
+                + t
+                  * m
+                  * m
+            )
     t2 = t2Nom / (den ** 2)
     res = 0.5 * (t1 + sqrt t2)
 
diff --git a/src/ELynx/Tree/Distribution/CoalescentContinuous.hs b/src/ELynx/Tree/Distribution/CoalescentContinuous.hs
--- a/src/ELynx/Tree/Distribution/CoalescentContinuous.hs
+++ b/src/ELynx/Tree/Distribution/CoalescentContinuous.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Distribution.CoalescentContinuous
 -- Description :  Distribution of coalescent times
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Distribution/TimeOfOrigin.hs b/src/ELynx/Tree/Distribution/TimeOfOrigin.hs
--- a/src/ELynx/Tree/Distribution/TimeOfOrigin.hs
+++ b/src/ELynx/Tree/Distribution/TimeOfOrigin.hs
@@ -4,7 +4,7 @@
 -- |
 --   Module      :  ELynx.Tree.Distribution.TimeOfOrigin
 --   Description :  Distribution of time of origin for birth and death trees
---   Copyright   :  (c) Dominik Schrempf 2021
+--   Copyright   :  2021 Dominik Schrempf
 --   License     :  GPL-3.0-or-later
 --
 --   Maintainer  :  dominik.schrempf@gmail.com
@@ -56,7 +56,7 @@
   | otherwise = te ** fromIntegral n
   where
     d = l - m
-    te = l * (1.0 - exp (- d * x)) / (l - m * exp (- d * x))
+    te = l * (1.0 - exp (-d * x)) / (l - m * exp (-d * x))
 
 instance D.ContDistr TimeOfOriginDistribution where
   density = density
@@ -70,7 +70,7 @@
   where
     d = l - m
     n = fromIntegral nn
-    ex = exp (- d * x)
+    ex = exp (-d * x)
     t1 = 1.0 - ex
     t2 = l - m * ex
 
@@ -79,12 +79,12 @@
 quantile :: TimeOfOriginDistribution -> Double -> Time
 quantile (TOD n' l m) p
   | p >= 0 && p <= 1 =
-    -1.0 / d * log (t1 / t2)
+      -1.0 / d * log (t1 / t2)
   | otherwise =
-    error $
-      "PointProcess.quantile: p must be in [0,1] range. Got: "
-        ++ show p
-        ++ "."
+      error $
+        "PointProcess.quantile: p must be in [0,1] range. Got: "
+          ++ show p
+          ++ "."
   where
     d = l - m
     n = fromIntegral n'
diff --git a/src/ELynx/Tree/Distribution/TimeOfOriginNearCritical.hs b/src/ELynx/Tree/Distribution/TimeOfOriginNearCritical.hs
--- a/src/ELynx/Tree/Distribution/TimeOfOriginNearCritical.hs
+++ b/src/ELynx/Tree/Distribution/TimeOfOriginNearCritical.hs
@@ -4,7 +4,7 @@
 -- |
 --   Module      :  ELynx.Tree.Distribution.TimeOfOriginNearCritical
 --   Description :  Distribution of time of origin for birth and death trees
---   Copyright   :  (c) Dominik Schrempf 2021
+--   Copyright   :  2021 Dominik Schrempf
 --   License     :  GPL-3.0-or-later
 --
 --   Maintainer  :  dominik.schrempf@gmail.com
@@ -80,15 +80,15 @@
 quantile :: TimeOfOriginNearCriticalDistribution -> Double -> Time
 quantile (TONCD n' l m) p
   | p >= 0 && p <= 1 =
-    t1 + t2nom / t2den
+      t1 + t2nom / t2den
   | otherwise =
-    error $
-      "PointProcess.quantile: p must be in [0,1] range. Got: "
-        ++ show p
-        ++ "."
+      error $
+        "PointProcess.quantile: p must be in [0,1] range. Got: "
+          ++ show p
+          ++ "."
   where
     n = fromIntegral n'
-    t1 = - p ** (1 / n) / ((-1 + p ** (1 / n)) * l)
+    t1 = -p ** (1 / n) / ((-1 + p ** (1 / n)) * l)
     t2nom = p ** (2 / n) * (m - l)
     t2den = 2 * (-1 + p ** (1 / n)) ** 2 * l ** 2
 
diff --git a/src/ELynx/Tree/Distribution/Types.hs b/src/ELynx/Tree/Distribution/Types.hs
--- a/src/ELynx/Tree/Distribution/Types.hs
+++ b/src/ELynx/Tree/Distribution/Types.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Distribution.Types
 -- Description :  Data types for distributions on trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Export/Newick.hs b/src/ELynx/Tree/Export/Newick.hs
--- a/src/ELynx/Tree/Export/Newick.hs
+++ b/src/ELynx/Tree/Export/Newick.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Export.Newick
 -- Description :  Export tree objects to Newick format
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Export/Nexus.hs b/src/ELynx/Tree/Export/Nexus.hs
--- a/src/ELynx/Tree/Export/Nexus.hs
+++ b/src/ELynx/Tree/Export/Nexus.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Export.Nexus
 -- Description :  Export trees to Nexus files
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Import/Newick.hs b/src/ELynx/Tree/Import/Newick.hs
--- a/src/ELynx/Tree/Import/Newick.hs
+++ b/src/ELynx/Tree/Import/Newick.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Import.Newick
 -- Description :  Import Newick trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -225,7 +225,8 @@
     *> optional brackets
     *> treeRevBayes
     <* char ';'
-    <* skipWhile isSpace <?> "newickRevBayes"
+    <* skipWhile isSpace
+    <?> "newickRevBayes"
 
 treeRevBayes :: Parser (Tree Phylo Name)
 treeRevBayes = branchedRevBayes <|> leafRevBayes <?> "treeRevBayes"
diff --git a/src/ELynx/Tree/Import/Nexus.hs b/src/ELynx/Tree/Import/Nexus.hs
--- a/src/ELynx/Tree/Import/Nexus.hs
+++ b/src/ELynx/Tree/Import/Nexus.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Import.Nexus
 -- Description :  Import trees from Nexus files
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Length.hs b/src/ELynx/Tree/Length.hs
--- a/src/ELynx/Tree/Length.hs
+++ b/src/ELynx/Tree/Length.hs
@@ -5,7 +5,7 @@
 -- |
 -- Module      :  ELynx.Tree.Length
 -- Description :  Labels having a length
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Mrca.hs b/src/ELynx/Tree/Mrca.hs
new file mode 100644
--- /dev/null
+++ b/src/ELynx/Tree/Mrca.hs
@@ -0,0 +1,112 @@
+-- |
+-- Module      :  ELynx.Tree.Mrca
+-- Description :  Most recent common ancestors
+-- Copyright   :  2022 Dominik Schrempf
+-- License     :  GPL-3.0-or-later
+--
+-- Maintainer  :  dominik.schrempf@gmail.com
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Creation date: Wed Jun 29 15:57:09 2022.
+--
+-- Specify nodes using most recent common ancestors (MRCA).
+module ELynx.Tree.Mrca
+  ( isAncestor,
+    isMrca,
+    getPathToMrca,
+    getTreeAtMrca,
+    findNode,
+  )
+where
+
+import Data.Either
+import Data.List
+import Data.Maybe
+import qualified Data.Set as S
+import ELynx.Tree.Rooted
+import ELynx.Tree.Zipper
+
+-- | Test if the root node of the given tree is an ancestor of the given leaves.
+isAncestor :: Ord a => S.Set a -> Tree e a -> Bool
+--                      True if an x of xs is not in the collection of leaves.
+--                False      if an x of xs is not in the collection of leaves. -> OK.
+isAncestor xs t = not $ any (`S.notMember` lvs) xs
+  where
+    lvs = S.fromList $ leaves t
+
+-- | Test if the root node of the given tree is the MRCA of the given leaves.
+isMrca :: Ord a => S.Set a -> Tree e a -> Bool
+--                                    True if any daughter forest is an ancestor.
+--                               False     if any daughter forest is an ancestor. -> OK.
+isMrca xs t = isAncestor xs t && not (any (isAncestor xs) (forest t))
+
+-- | Get the path to the MRCA of the given leaves on the given tree.
+--
+-- Return 'Left' if:
+--
+-- - The tree has duplicate leaves.
+--
+-- - The MRCA cannot be found.
+getPathToMrca :: (Ord a, Show a) => S.Set a -> Tree e a -> Either String Path
+getPathToMrca ss tr
+  | duplicateLeaves tr = Left "getPathToMrca: Tree contains duplicate leaves."
+  | otherwise = tail <$> go 0 tr
+  where
+    go i t
+      | isMrca ss t = Right [i]
+      --                                    One path will be (Right p).
+      | isAncestor ss t =
+          case find isRight [go j t' | (j, t') <- zip [0 ..] (forest t)] of
+            -- Use 'error' because this should never happen since one subtree has
+            -- to contain the MRCA.
+            Nothing -> error $ "getPathToMrca: BUG; I am ancestor but no MRCA found for: " <> show ss
+            Just xs -> fmap (i :) xs
+      | otherwise = Left $ "getPathToMrca: Could not get MRCA for: " <> show ss <> "."
+
+getTreeAtMrca :: (Ord a, Show a) => S.Set a -> Tree e a -> Either String (Tree e a)
+getTreeAtMrca ss tr
+  | duplicateLeaves tr = Left "getTreeAtMrca: Tree contains duplicate leaves."
+  | otherwise = go tr
+  where
+    go t
+      | isMrca ss t = Right t
+      --                                One tree will be (Right t).
+      | isAncestor ss t = case find isRight $ map go (forest t) of
+          -- Use 'error' because this should never happen since one subtree has
+          -- to contain the MRCA.
+          Nothing -> error $ "getTreeAtMrca: BUG; I am ancestor but no MRCA found for: " <> show ss
+          Just x -> x
+      | otherwise = Left $ "getTreeAtMrca: Could not get MRCA for: " <> show ss <> "."
+
+-- | Find a node on a tree.
+--
+-- If the node is found, the node is specified by the MRCA of the returned set
+-- of leaves. The set will contain one element if the node is a leaf, or two
+-- elements, if the node is internal.
+--
+-- Return 'Left' if:
+--
+-- - The tree has duplicate labels.
+--
+-- - The node cannot be found.
+--
+-- - The node is a degree two node.
+findNode :: (Ord a, Show a) => a -> Tree e a -> Either String (S.Set a)
+findNode n t
+  | duplicateLabels t = Left "findNode: tree contains duplicate labels"
+  | otherwise = case go n t of
+      Nothing -> Left $ "findNode: node not found: " <> show n
+      Just x -> x
+  where
+    go x (Node _ y ts)
+      | x == y = case ts of
+          [] -> Just $ Right $ S.singleton x
+          (l : r : _) -> Just $ Right $ S.fromList [head $ leaves l, head $ leaves r]
+          _ -> Just $ Left $ "findNode: degree two node found" <> show n
+      | otherwise = case catMaybes $ map (go x) ts of
+          [] -> Nothing
+          [z] -> Just z
+          -- Use 'error' because this should never happen since we check for
+          -- duplicate labels.
+          _ -> error $ "findNode: BUG; more internal nodes found" <> show n
diff --git a/src/ELynx/Tree/Name.hs b/src/ELynx/Tree/Name.hs
--- a/src/ELynx/Tree/Name.hs
+++ b/src/ELynx/Tree/Name.hs
@@ -5,7 +5,7 @@
 -- |
 -- Module      :  ELynx.Tree.Name
 -- Description :  Trees with named nodes
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Parallel.hs b/src/ELynx/Tree/Parallel.hs
--- a/src/ELynx/Tree/Parallel.hs
+++ b/src/ELynx/Tree/Parallel.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Parallel
 -- Description :  Evaluation strategies for trees
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -40,11 +40,11 @@
 parTree :: (NFData e, NFData a) => Int -> Strategy (Tree e a)
 parTree n t@(Node br lb ts)
   | n == 1 = do
-    ts' <- myParList rdeepseq ts
-    return $ Node br lb ts'
+      ts' <- myParList rdeepseq ts
+      return $ Node br lb ts'
   | n >= 2 = do
-    ts' <- myParList (parTree (n -1)) ts
-    return $ Node br lb ts'
+      ts' <- myParList (parTree (n - 1)) ts
+      return $ Node br lb ts'
   | otherwise = rdeepseq t
 
 branchFoldMap :: (e -> f) -> (f -> f -> f) -> Tree e a -> f
diff --git a/src/ELynx/Tree/Partition.hs b/src/ELynx/Tree/Partition.hs
--- a/src/ELynx/Tree/Partition.hs
+++ b/src/ELynx/Tree/Partition.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Partition
 -- Description :  Partitions on rose trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -109,8 +109,8 @@
 partitions' _ (Node _ _ []) = S.empty
 partitions' p t@(Node _ _ ts) =
   S.unions $
-    either (const S.empty) S.singleton (pt (p : map label ts)) :
-    zipWith partitions' cs ts
+    either (const S.empty) S.singleton (pt (p : map label ts))
+      : zipWith partitions' cs ts
   where
     cs = getComplementaryLeaves p t
 
diff --git a/src/ELynx/Tree/Phylogeny.hs b/src/ELynx/Tree/Phylogeny.hs
--- a/src/ELynx/Tree/Phylogeny.hs
+++ b/src/ELynx/Tree/Phylogeny.hs
@@ -5,7 +5,7 @@
 -- |
 -- Module      :  ELynx.Tree.Phylogeny
 -- Description :  Phylogenetic trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -120,8 +120,8 @@
 intersect ts
   | S.null lvsCommon = Left "intersect: Intersection of leaves is empty."
   | otherwise = case sequence [dropLeavesWith (predicate ls) t | (ls, t) <- zip leavesToDrop ts] of
-    Nothing -> Left "intersect: A tree is empty."
-    Just ts' -> Right ts'
+      Nothing -> Left "intersect: A tree is empty."
+      Just ts' -> Right ts'
   where
     -- Leaf sets.
     lvss = map (S.fromList . leaves) ts
@@ -186,10 +186,10 @@
   | length lvLst /= S.size lvSet = Left "rootAt: Tree has duplicate leaves."
   | toSet b /= lvSet = Left "rootAt: Bipartition does not match leaves of tree."
   | otherwise = do
-    ts <- roots t
-    case find (\x -> bipartition x == Right b) ts of
-      Nothing -> Left "rootAt': Bipartition not found on tree."
-      Just t' -> Right t'
+      ts <- roots t
+      case find (\x -> bipartition x == Right b) ts of
+        Nothing -> Left "rootAt': Bipartition not found on tree."
+        Just t' -> Right t'
   where
     lvLst = leaves t
     lvSet = S.fromList $ leaves t
@@ -289,7 +289,7 @@
     tR = Node bL' c $ tail ts
 
 complementaryForests :: Tree e a -> Forest e a -> [Forest e a]
-complementaryForests t ts = [t : take i ts ++ drop (i + 1) ts | i <- [0 .. (n -1)]]
+complementaryForests t ts = [t : take i ts ++ drop (i + 1) ts | i <- [0 .. (n - 1)]]
   where
     n = length ts
 
diff --git a/src/ELynx/Tree/Rooted.hs b/src/ELynx/Tree/Rooted.hs
--- a/src/ELynx/Tree/Rooted.hs
+++ b/src/ELynx/Tree/Rooted.hs
@@ -6,7 +6,7 @@
 -- |
 -- Module      :  ELynx.Tree.Rooted
 -- Description :  Rooted trees with labeled branches
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -77,6 +77,7 @@
     setLabel,
     modifyLabel,
     labels,
+    duplicateLabels,
     setLabels,
     identify,
 
@@ -295,6 +296,10 @@
   where
     squish (Node _ lb ts) xs = lb : foldr squish xs ts
 
+-- | Check if a tree has duplicate labels.
+duplicateLabels :: Ord a => Tree e a -> Bool
+duplicateLabels = duplicates . labels
+
 -- | Set node labels in pre-order.
 --
 -- Return 'Nothing' if the provided list of node labels is too short.
@@ -353,9 +358,9 @@
 dropNodesWith p (Node br lb ts)
   | p lb = Nothing
   | otherwise =
-    if null ts'
-      then Nothing
-      else Just $ Node br lb ts'
+      if null ts'
+        then Nothing
+        else Just $ Node br lb ts'
   where
     ts' = mapMaybe (dropNodesWith p) ts
 
diff --git a/src/ELynx/Tree/Simulate/Coalescent.hs b/src/ELynx/Tree/Simulate/Coalescent.hs
--- a/src/ELynx/Tree/Simulate/Coalescent.hs
+++ b/src/ELynx/Tree/Simulate/Coalescent.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Simulate.Coalescent
 -- Description :  Generate coalescent trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -14,46 +14,45 @@
   )
 where
 
-import Control.Monad.Primitive
 import ELynx.Tree.Distribution.CoalescentContinuous
 import ELynx.Tree.Length
 import ELynx.Tree.Rooted
 import Statistics.Distribution
-import System.Random.MWC
+import System.Random.Stateful
 
 -- | Simulate a coalescent tree with @n@ leaves. The branch lengths are in units
 -- of effective population size.
 simulate ::
-  (PrimMonad m) =>
+  StatefulGen g m =>
   -- | Number of leaves.
   Int ->
-  Gen (PrimState m) ->
+  g ->
   m (Tree Length Int)
 simulate n = simulate' n 0 trs
   where
     trs = [Node 0 i [] | i <- [0 .. n - 1]]
 
 simulate' ::
-  (PrimMonad m) =>
+  StatefulGen g m =>
   Int ->
   Int ->
   Forest Length Int ->
-  Gen (PrimState m) ->
+  g ->
   m (Tree Length Int)
 simulate' n a trs g
   | n <= 0 = error "Cannot construct trees without leaves."
   | n == 1 && length trs /= 1 = error "Too many trees provided."
   | n == 1 && length trs == 1 = return $ head trs
   | otherwise = do
-    -- Indices of the leaves to join will be i-1 and i.
-    i <- uniformR (1, n - 1) g
-    -- The time of the coalescent event.
-    t <- toLengthUnsafe <$> genContVar (coalescentDistributionCont n) g
-    let trs' = map (modifyStem (+ t)) trs -- Move time 't' up on the tree.
-        tl = trs' !! (i - 1)
-        tr = trs' !! i
-        -- Join the two chosen trees.
-        tm = Node 0 a [tl, tr]
-        -- Take the trees on the left, the merged tree, and the trees on the right.
-        trs'' = take (i - 1) trs' ++ [tm] ++ drop (i + 1) trs'
-    simulate' (n - 1) a trs'' g
+      -- Indices of the leaves to join will be i-1 and i.
+      i <- uniformRM (1, n - 1) g
+      -- The time of the coalescent event.
+      t <- toLengthUnsafe <$> genContVar (coalescentDistributionCont n) g
+      let trs' = map (modifyStem (+ t)) trs -- Move time 't' up on the tree.
+          tl = trs' !! (i - 1)
+          tr = trs' !! i
+          -- Join the two chosen trees.
+          tm = Node 0 a [tl, tr]
+          -- Take the trees on the left, the merged tree, and the trees on the right.
+          trs'' = take (i - 1) trs' ++ [tm] ++ drop (i + 1) trs'
+      simulate' (n - 1) a trs'' g
diff --git a/src/ELynx/Tree/Simulate/PointProcess.hs b/src/ELynx/Tree/Simulate/PointProcess.hs
--- a/src/ELynx/Tree/Simulate/PointProcess.hs
+++ b/src/ELynx/Tree/Simulate/PointProcess.hs
@@ -3,7 +3,7 @@
 -- |
 --   Module      :  ELynx.Tree.Simulate.PointProcess
 --   Description :  Point process and functions
---   Copyright   :  (c) Dominik Schrempf 2021
+--   Copyright   :  2021 Dominik Schrempf
 --   License     :  GPL-3.0-or-later
 --
 --   Maintainer  :  dominik.schrempf@gmail.com
@@ -28,7 +28,6 @@
 where
 
 import Control.Monad
-import Control.Monad.Primitive
 import Data.Function
 import Data.List
 import Data.Sequence (Seq)
@@ -43,9 +42,7 @@
 import ELynx.Tree.Length
 import ELynx.Tree.Rooted
 import qualified Statistics.Distribution as D
-  ( genContVar,
-  )
-import System.Random.MWC
+import System.Random.Stateful
 
 -- Require near critical process if birth and death rates are closer than this value.
 epsNearCriticalPointProcess :: Double
@@ -67,10 +64,10 @@
 sortListWithIndices xs = sortBy (compare `on` fst) $ zip xs ([0 ..] :: [Int])
 
 -- Insert element into random position of list.
-randomInsertList :: PrimMonad m => a -> [a] -> Gen (PrimState m) -> m [a]
+randomInsertList :: StatefulGen g m => a -> [a] -> g -> m [a]
 randomInsertList e v g = do
   let l = length v
-  i <- uniformR (0, l) g
+  i <- uniformRM (0, l) g
   return $ take i v ++ [e] ++ drop i v
 
 -- | A __point process__ for \(n\) points and of age \(t_{or}\) is defined as
@@ -98,7 +95,7 @@
 -- | Sample a point process using the 'BirthDeathDistribution'. The names of the
 -- points will be integers.
 simulate ::
-  (PrimMonad m) =>
+  StatefulGen g m =>
   -- | Number of points (samples).
   Int ->
   -- | Time of origin or MRCA.
@@ -107,58 +104,57 @@
   Rate ->
   -- | Death rate.
   Rate ->
-  -- | Generator.
-  Gen (PrimState m) ->
+  g ->
   m (PointProcess Int Double)
 simulate n ts l m g
   | n < 1 = error "Number of samples needs to be one or larger."
   | l < 0.0 = error "Birth rate needs to be positive."
   | otherwise = case ts of
-    Random -> simulateRandom n l m g
-    Origin t -> simulateOrigin n t l m g
-    Mrca t -> simulateMrca n t l m g
+      Random -> simulateRandom n l m g
+      Origin t -> simulateOrigin n t l m g
+      Mrca t -> simulateMrca n t l m g
 
 -- No time of origin given. We also don't need to take care of the conditioning
 -- (origin or MRCA).
 simulateRandom ::
-  PrimMonad m =>
+  StatefulGen g m =>
   Int ->
   Double ->
   Double ->
-  Gen (PrimState m) ->
+  g ->
   m (PointProcess Int Double)
 simulateRandom n l m g
   | -- There is no formula for the over-critical process.
     m > l =
-    error
-      "simulateRandom: Please specify height if mu > lambda."
+      error
+        "simulateRandom: Please specify height if mu > lambda."
   | -- For the critical process, we have no idea about the time of origin, but can
     -- use a specially derived distribution.
     m =~= l =
-    do
-      !vs <- replicateM (n - 1) (D.genContVar (BDCNTD l) g)
-      -- The length of the root branch will be 0.
-      let t = maximum vs
-      return $ PointProcess [0 .. (n - 1)] vs t
+      do
+        !vs <- replicateM (n - 1) (D.genContVar (BDCNTD l) g)
+        -- The length of the root branch will be 0.
+        let t = maximum vs
+        return $ PointProcess [0 .. (n - 1)] vs t
   | -- For the near critical process, we use a special distribution.
     abs (m - l) <= epsNearCriticalTimeOfOrigin =
-    do
-      t <- D.genContVar (TONCD n l m) g
-      simulateOrigin n t l m g
+      do
+        t <- D.genContVar (TONCD n l m) g
+        simulateOrigin n t l m g
   | -- For a sub-critical branching process, we can use the formula from Tanja Stadler.
     otherwise =
-    do
-      t <- D.genContVar (TOD n l m) g
-      simulateOrigin n t l m g
+      do
+        t <- D.genContVar (TOD n l m) g
+        simulateOrigin n t l m g
 
 -- Time of origin is given.
 simulateOrigin ::
-  PrimMonad m =>
+  StatefulGen g m =>
   Int ->
   Time ->
   Double ->
   Double ->
-  Gen (PrimState m) ->
+  g ->
   m (PointProcess Int Double)
 simulateOrigin n t l m g
   | t < 0.0 = error "simulateOrigin: Time of origin needs to be positive."
@@ -171,38 +167,38 @@
     -- 2. The near critical branching process.
     -- 3. Normal values :).
     m =~= l = do
-    !vs <- replicateM (n - 1) (D.genContVar (BDCD t l) g)
-    return $ PointProcess [0 .. (n - 1)] vs t
+      !vs <- replicateM (n - 1) (D.genContVar (BDCD t l) g)
+      return $ PointProcess [0 .. (n - 1)] vs t
   | abs (m - l) <= epsNearCriticalPointProcess = do
-    !vs <- replicateM (n - 1) (D.genContVar (BDNCD t l m) g)
-    return $ PointProcess [0 .. (n - 1)] vs t
+      !vs <- replicateM (n - 1) (D.genContVar (BDNCD t l m) g)
+      return $ PointProcess [0 .. (n - 1)] vs t
   | otherwise = do
-    !vs <- replicateM (n - 1) (D.genContVar (BDD t l m) g)
-    return $ PointProcess [0 .. (n - 1)] vs t
+      !vs <- replicateM (n - 1) (D.genContVar (BDD t l m) g)
+      return $ PointProcess [0 .. (n - 1)] vs t
 
 -- Time of Mrca is given.
 simulateMrca ::
-  PrimMonad m =>
+  StatefulGen g m =>
   Int ->
   Time ->
   Double ->
   Double ->
-  Gen (PrimState m) ->
+  g ->
   m (PointProcess Int Double)
 simulateMrca n t l m g
   | t < 0.0 = error "simulateMrca: Time of MRCA needs to be positive."
   | m =~= l = do
-    !vs <- replicateM (n - 2) (D.genContVar (BDCD t l) g)
-    vs' <- randomInsertList t vs g
-    return $ PointProcess [0 .. (n - 1)] vs' t
+      !vs <- replicateM (n - 2) (D.genContVar (BDCD t l) g)
+      vs' <- randomInsertList t vs g
+      return $ PointProcess [0 .. (n - 1)] vs' t
   | abs (m - l) <= epsNearCriticalPointProcess = do
-    !vs <- replicateM (n - 2) (D.genContVar (BDNCD t l m) g)
-    vs' <- randomInsertList t vs g
-    return $ PointProcess [0 .. (n - 1)] vs' t
+      !vs <- replicateM (n - 2) (D.genContVar (BDNCD t l m) g)
+      vs' <- randomInsertList t vs g
+      return $ PointProcess [0 .. (n - 1)] vs' t
   | otherwise = do
-    !vs <- replicateM (n - 2) (D.genContVar (BDD t l m) g)
-    vs' <- randomInsertList t vs g
-    return $ PointProcess [0 .. (n - 1)] vs' t
+      !vs <- replicateM (n - 2) (D.genContVar (BDD t l m) g)
+      vs' <- randomInsertList t vs g
+      return $ PointProcess [0 .. (n - 1)] vs' t
 
 -- Sort the values of a point process and their indices to be (the indices
 -- that they will have while creating the tree).
@@ -226,7 +222,7 @@
 
 -- | See 'simulateReconstructedTree', but n times.
 simulateNReconstructedTrees ::
-  (PrimMonad m) =>
+  (StatefulGen g m) =>
   -- | Number of trees
   Int ->
   -- | Number of points (samples)
@@ -237,8 +233,7 @@
   Rate ->
   -- | Death rate
   Rate ->
-  -- | Generator (see 'System.Random.MWC')
-  Gen (PrimState m) ->
+  g ->
   m (Forest Length Int)
 simulateNReconstructedTrees nT nP t l m g
   | nT <= 0 = return []
@@ -248,7 +243,7 @@
 -- 'toReconstructedTree') possibly with specific height and a fixed number of
 -- leaves according to the birth and death process.
 simulateReconstructedTree ::
-  (PrimMonad m) =>
+  StatefulGen g m =>
   -- | Number of points (samples)
   Int ->
   -- | Time of origin or MRCA
@@ -257,8 +252,7 @@
   Rate ->
   -- | Death rate
   Rate ->
-  -- | Generator (see 'System.Random.MWC')
-  Gen (PrimState m) ->
+  g ->
   m (Tree Length Int)
 simulateReconstructedTree n t l m g = do
   PointProcess ns vs o <- simulate n t l m g
@@ -284,7 +278,7 @@
   | -- -- Test is deactivated.
     -- -- | otherwise = if isReconstructed treeOrigin then treeOrigin else error "Error in algorithm."
     otherwise =
-    treeOrigin
+      treeOrigin
   where
     (vsSorted, isSorted) = sortPP pp
     !lvs = S.fromList [Node 0 p [] | p <- ps]
diff --git a/src/ELynx/Tree/Splittable.hs b/src/ELynx/Tree/Splittable.hs
--- a/src/ELynx/Tree/Splittable.hs
+++ b/src/ELynx/Tree/Splittable.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Splittable
 -- Description :  Splittable branch labels
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Support.hs b/src/ELynx/Tree/Support.hs
--- a/src/ELynx/Tree/Support.hs
+++ b/src/ELynx/Tree/Support.hs
@@ -5,7 +5,7 @@
 -- |
 -- Module      :  ELynx.Tree.Support
 -- Description :  Labels with support values
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/src/ELynx/Tree/Zipper.hs b/src/ELynx/Tree/Zipper.hs
--- a/src/ELynx/Tree/Zipper.hs
+++ b/src/ELynx/Tree/Zipper.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Tree.Zipper
 -- Description :  Zippers on rooted rose trees with branch labels
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
@@ -133,13 +133,13 @@
     | null ts -> Nothing
     | length ts <= n -> Nothing
     | otherwise ->
-      Just $
-        Pos
-          { current = head rs',
-            before = reverse ls',
-            after = tail rs',
-            parents = (before pos, br, lb, after pos) : parents pos
-          }
+        Just $
+          Pos
+            { current = head rs',
+              before = reverse ls',
+              after = tail rs',
+              parents = (before pos, br, lb, after pos) : parents pos
+            }
     where
       (ls', rs') = splitAt n ts
 
@@ -151,12 +151,12 @@
     | null ts -> error "goChildUnsafe: Forest is empty."
     | length ts <= n -> error "goChildUnsafe: Forest is too short."
     | otherwise ->
-      Pos
-        { current = head rs',
-          before = reverse ls',
-          after = tail rs',
-          parents = (before pos, br, lb, after pos) : parents pos
-        }
+        Pos
+          { current = head rs',
+            before = reverse ls',
+            after = tail rs',
+            parents = (before pos, br, lb, after pos) : parents pos
+          }
     where
       (ls', rs') = splitAt n ts
 
diff --git a/test/ELynx/ClassLaws.hs b/test/ELynx/ClassLaws.hs
--- a/test/ELynx/ClassLaws.hs
+++ b/test/ELynx/ClassLaws.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.ClassLaws
 -- Description :  Unit tests for ELynx.ClassLaws
--- Copyright   :  (c) 2021 Dominik Schrempf
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Topology/Arbitrary.hs b/test/ELynx/Topology/Arbitrary.hs
--- a/test/ELynx/Topology/Arbitrary.hs
+++ b/test/ELynx/Topology/Arbitrary.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Topology.Arbitrary
 -- Description :  Arbitrary instances for topologies
--- Copyright   :  (c) 2021 Dominik Schrempf
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Topology/RootedSpec.hs b/test/ELynx/Topology/RootedSpec.hs
--- a/test/ELynx/Topology/RootedSpec.hs
+++ b/test/ELynx/Topology/RootedSpec.hs
@@ -1,7 +1,7 @@
 -- |
 -- Module      :  ELynx.Topology.RootedSpec
 -- Description :  Unit tests for ELynx.Topology.Rooted
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/Arbitrary.hs b/test/ELynx/Tree/Arbitrary.hs
--- a/test/ELynx/Tree/Arbitrary.hs
+++ b/test/ELynx/Tree/Arbitrary.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Arbitrary
 -- Description :  Arbitrary instances for trees
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/BipartitionSpec.hs b/test/ELynx/Tree/BipartitionSpec.hs
--- a/test/ELynx/Tree/BipartitionSpec.hs
+++ b/test/ELynx/Tree/BipartitionSpec.hs
@@ -2,7 +2,7 @@
 
 -- |
 -- Module      :  ELynx.Tree.BipartitionSpec
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/DistanceSpec.hs b/test/ELynx/Tree/DistanceSpec.hs
--- a/test/ELynx/Tree/DistanceSpec.hs
+++ b/test/ELynx/Tree/DistanceSpec.hs
@@ -3,7 +3,7 @@
 
 -- |
 -- Module      :  ELynx.Tree.DistanceSpec
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/Export/NewickSpec.hs b/test/ELynx/Tree/Export/NewickSpec.hs
--- a/test/ELynx/Tree/Export/NewickSpec.hs
+++ b/test/ELynx/Tree/Export/NewickSpec.hs
@@ -2,7 +2,7 @@
 
 -- |
 -- Module      :  ELynx.Tree.Export.NewickSpec
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/Export/NexusSpec.hs b/test/ELynx/Tree/Export/NexusSpec.hs
--- a/test/ELynx/Tree/Export/NexusSpec.hs
+++ b/test/ELynx/Tree/Export/NexusSpec.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Export.NexusSpec
 -- Description :  Test export of trees in Nexus files
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/Import/NewickSpec.hs b/test/ELynx/Tree/Import/NewickSpec.hs
--- a/test/ELynx/Tree/Import/NewickSpec.hs
+++ b/test/ELynx/Tree/Import/NewickSpec.hs
@@ -2,7 +2,7 @@
 
 -- |
 -- Module      :  ELynx.Tree.Import.NewickSpec
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/Import/NexusSpec.hs b/test/ELynx/Tree/Import/NexusSpec.hs
--- a/test/ELynx/Tree/Import/NexusSpec.hs
+++ b/test/ELynx/Tree/Import/NexusSpec.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.Import.NexusSpec
 -- Description :  Test import of trees in Nexus files
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/PartitionSpec.hs b/test/ELynx/Tree/PartitionSpec.hs
--- a/test/ELynx/Tree/PartitionSpec.hs
+++ b/test/ELynx/Tree/PartitionSpec.hs
@@ -2,7 +2,7 @@
 
 -- |
 -- Module      :  ELynx.Tree.PartitionSpec
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/PhylogenySpec.hs b/test/ELynx/Tree/PhylogenySpec.hs
--- a/test/ELynx/Tree/PhylogenySpec.hs
+++ b/test/ELynx/Tree/PhylogenySpec.hs
@@ -4,7 +4,7 @@
 -- |
 -- Module      :  ELynx.Tree.PhylogenySpec
 -- Description :  Unit tests for ELynx.Tree.Phylogeny
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/RootedSpec.hs b/test/ELynx/Tree/RootedSpec.hs
--- a/test/ELynx/Tree/RootedSpec.hs
+++ b/test/ELynx/Tree/RootedSpec.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.RootedSpec
 -- Description :  Unit tests for ELynx.Tree.Rooted
--- Copyright   :  (c) Dominik Schrempf 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com
diff --git a/test/ELynx/Tree/SupportSpec.hs b/test/ELynx/Tree/SupportSpec.hs
--- a/test/ELynx/Tree/SupportSpec.hs
+++ b/test/ELynx/Tree/SupportSpec.hs
@@ -3,7 +3,7 @@
 -- |
 -- Module      :  ELynx.Tree.SupportSpec
 -- Description :  Unit tests for ELynx.Tree.SupportSpec
--- Copyright   :  (c) Dominik Schrempf, 2021
+-- Copyright   :  2021 Dominik Schrempf
 -- License     :  GPL-3.0-or-later
 --
 -- Maintainer  :  dominik.schrempf@gmail.com