diff --git a/pred-trie.cabal b/pred-trie.cabal
--- a/pred-trie.cabal
+++ b/pred-trie.cabal
@@ -1,13 +1,15 @@
--- This file has been generated from package.yaml by hpack version 0.21.2.
+cabal-version: 1.12
+
+-- This file has been generated from package.yaml by hpack version 0.31.0.
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 03b4ea47e57ecfda68de39c93f569f4b5f8a076b14a22dc5ba822e6d4c71cba9
+-- hash: 375539d0dc78092f6f728d3b9279b9efedf1eed0cbde58250ccdd0dbce6a8f6d
 
 name:           pred-trie
-version:        0.6.0.1
+version:        0.6.1
 synopsis:       Predicative tries
-description:    Please see the README on Github at <https://git.localcooking.com/tooling/pred-trie#readme>
+description:    Please see the README on Github at <https://github.com/athanclark/pred-trie#readme>
 category:       Data
 homepage:       https://github.com/athanclark/pred-trie#readme
 bug-reports:    https://github.com/athanclark/pred-trie/issues
@@ -17,8 +19,6 @@
 license:        BSD3
 license-file:   LICENSE
 build-type:     Simple
-cabal-version:  >= 1.10
-
 extra-source-files:
     README.md
 
@@ -40,7 +40,7 @@
   ghc-options: -Wall
   build-depends:
       QuickCheck >=2.9.2
-    , base >=4.8 && <5.0
+    , base >=4.11 && <5.0
     , containers
     , deepseq
     , hashable
@@ -50,7 +50,7 @@
     , pred-set
     , semigroups
     , strict
-    , tries >=0.0.5
+    , tries >=0.0.6
     , unordered-containers
   default-language: Haskell2010
 
@@ -82,7 +82,7 @@
     , tasty-hunit
     , tasty-quickcheck
     , text
-    , tries >=0.0.5
+    , tries >=0.0.6
     , unordered-containers
   default-language: Haskell2010
 
@@ -111,6 +111,6 @@
     , sets
     , strict
     , text
-    , tries >=0.0.5
+    , tries >=0.0.6
     , unordered-containers
   default-language: Haskell2010
diff --git a/src/Data/Trie/Pred/Base.hs b/src/Data/Trie/Pred/Base.hs
--- a/src/Data/Trie/Pred/Base.hs
+++ b/src/Data/Trie/Pred/Base.hs
@@ -107,10 +107,14 @@
 
 instance ( Hashable k
          , Eq k
+         ) => Semigroup (PredTrie k a) where
+  (PredTrie ls1 ps1) <> (PredTrie ls2 ps2) =
+    PredTrie (ls1 <> ls2) (ps1 <> ps2)
+
+instance ( Hashable k
+         , Eq k
          ) => Monoid (PredTrie k a) where
   mempty = PredTrie mempty mempty
-  mappend (PredTrie ls1 ps1) (PredTrie ls2 ps2) =
-    PredTrie (ls1 <> ls2) (ps1 <> ps2)
 
 emptyPT :: PredTrie k a
 emptyPT = PredTrie HT.empty (PredStep HMS.empty)
@@ -201,10 +205,15 @@
 
 instance ( Hashable k
          , Eq k
+         ) => Semigroup (RootedPredTrie k a) where
+  (RootedPredTrie mx xs) <> (RootedPredTrie my ys) = RootedPredTrie
+    (getLast (Last mx <> Last my)) (xs <> ys)
+
+
+instance ( Hashable k
+         , Eq k
          ) => Monoid (RootedPredTrie k a) where
   mempty = emptyRPT
-  mappend (RootedPredTrie mx xs) (RootedPredTrie my ys) = RootedPredTrie
-    (getLast (Last mx <> Last my)) (xs <> ys)
 
 
 emptyRPT :: RootedPredTrie k a
diff --git a/src/Data/Trie/Pred/Base/Step.hs b/src/Data/Trie/Pred/Base/Step.hs
--- a/src/Data/Trie/Pred/Base/Step.hs
+++ b/src/Data/Trie/Pred/Base/Step.hs
@@ -28,6 +28,7 @@
 
 import Data.Data (Typeable)
 import Data.Monoid (First (..), (<>))
+import Data.Semigroup (Semigroup)
 import Data.Maybe (maybe)
 import Data.Hashable (Hashable)
 import Data.HashMap.Strict (HashMap)
@@ -109,9 +110,13 @@
 
 instance ( Eq k
          , Hashable k
+         ) => Semigroup (PredStep k c s a) where
+  (<>) = unionPred
+
+instance ( Eq k
+         , Hashable k
          ) => Monoid (PredStep k c s a) where
   mempty  = PredStep HMS.empty
-  mappend = unionPred
 
 -- | overwrite on the right
 unionPred :: ( Eq k