diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,15 @@
+## Version 1.0.3 (2020-06-26)
+
+- Don't swallow errors if we can't find the source file ([#387][387], [@HuwCampbell][HuwCampbell])
+- Add `Property.evalNF` ([#384][384], [@dcastro][dcastro])
+- Add `Gen.either` and `Gen.either_` ([#382][382], [@dcastro][dcastro])
+- Add `filterT`, `justT`, and `mapMaybeT` to `Gen` exports ([#366][366], [@kquick][kquick])
+- Bump pretty-show to 1.10 which supports quasi-quotes ([#365][365], [@jacobstanley][jacobstanley])
+- Remove `undefined` in `GenT`'s `MonadWriter` instance ([#344][344], [@HuwCampbell][HuwCampbell])
+- Make `Tree.interleave` logarithmtic rather than linear ([#313][313], [@edsko][edsko])
+
 ## Version 1.0.2 (2020-01-10)
+- Support GHC 8.10  ([#376][376], [@sjakobi][sjakobi])
 - Speed up `Tree.splits` ([#349][349], [@treeowl][treeowl])
 - Speed up `Gen.shuffle` ([#348][348], [@treeowl][treeowl])
 - Add docs on the bounds of `Size` ([#346][346], [@chris-martin][chris-martin])
@@ -168,14 +179,30 @@
 [treeowl]:
   https://github.com/treeowl
 [tomjaguarpaw]:
-  https://github.com/tomjaguarpaw 
+  https://github.com/tomjaguarpaw
 [symbiont-sam-halliday]:
   https://github.com/symbiont-sam-halliday
 [sshine]:
   https://github.com/sshine
 [stolyaroleh]:
   https://github.com/stolyaroleh
+[kquick]:
+  https://github.com/kquick
+[dcastro]:
+  https://github.com/dcastro
 
+[387]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/387
+[384]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/384
+[382]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/382
+[376]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/376
+[366]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/366
+[365]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/365
 [349]:
   https://github.com/hedgehogqa/haskell-hedgehog/pull/349
 [348]:
@@ -184,6 +211,8 @@
   https://github.com/hedgehogqa/haskell-hedgehog/pull/346
 [345]:
   https://github.com/hedgehogqa/haskell-hedgehog/pull/345
+[344]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/344
 [339]:
   https://github.com/hedgehogqa/haskell-hedgehog/pull/339
 [332]:
@@ -196,6 +225,8 @@
   https://github.com/hedgehogqa/haskell-hedgehog/pull/321
 [319]:
   https://github.com/hedgehogqa/haskell-hedgehog/pull/319
+[313]:
+  https://github.com/hedgehogqa/haskell-hedgehog/pull/313
 [308]:
   https://github.com/hedgehogqa/haskell-hedgehog/pull/308
 [303]:
diff --git a/hedgehog.cabal b/hedgehog.cabal
--- a/hedgehog.cabal
+++ b/hedgehog.cabal
@@ -1,4 +1,4 @@
-version: 1.0.2
+version: 1.0.3
 
 name:
   hedgehog
@@ -29,14 +29,16 @@
 license-file:
   LICENSE
 cabal-version:
-  >= 1.8
+  >= 1.10
 build-type:
   Simple
 tested-with:
     GHC == 8.0.2
   , GHC == 8.2.2
   , GHC == 8.4.4
-  , GHC == 8.6.4
+  , GHC == 8.6.5
+  , GHC == 8.8.3
+  , GHC == 8.10.1
 extra-source-files:
   README.md
   CHANGELOG.md
@@ -54,6 +56,7 @@
     , bytestring                      >= 0.10       && < 0.11
     , concurrent-output               >= 1.7        && < 1.11
     , containers                      >= 0.4        && < 0.7
+    , deepseq                         >= 1.1.0.0    && < 1.5
     , directory                       >= 1.2        && < 1.4
     , erf                             >= 2.0        && < 2.1
     , exceptions                      >= 0.7        && < 0.11
@@ -62,13 +65,13 @@
     , mmorph                          >= 1.0        && < 1.2
     , monad-control                   >= 1.0        && < 1.1
     , mtl                             >= 2.1        && < 2.3
-    , pretty-show                     >= 1.6        && < 1.10
+    , pretty-show                     >= 1.6        && < 1.11
     , primitive                       >= 0.6        && < 0.8
     , random                          >= 1.1        && < 1.2
     , resourcet                       >= 1.1        && < 1.3
     , semigroups                      >= 0.16       && < 0.20
     , stm                             >= 2.4        && < 2.6
-    , template-haskell                >= 2.10       && < 2.16
+    , template-haskell                >= 2.10       && < 2.17
     , text                            >= 1.1        && < 1.3
     , time                            >= 1.4        && < 1.10
     , transformers                    >= 0.5        && < 0.6
@@ -97,6 +100,7 @@
     Hedgehog.Internal.Gen
     Hedgehog.Internal.HTraversable
     Hedgehog.Internal.Opaque
+    Hedgehog.Internal.Prelude
     Hedgehog.Internal.Property
     Hedgehog.Internal.Queue
     Hedgehog.Internal.Range
@@ -112,6 +116,9 @@
     Hedgehog.Internal.Tree
     Hedgehog.Internal.Tripping
 
+  default-language:
+    Haskell2010
+
 test-suite test
   type:
     exitcode-stdio-1.0
@@ -140,7 +147,10 @@
     , containers                      >= 0.4        && < 0.7
     , mmorph                          >= 1.0        && < 1.2
     , mtl                             >= 2.1        && < 2.3
-    , pretty-show                     >= 1.6        && < 1.10
+    , pretty-show                     >= 1.6        && < 1.11
     , semigroups                      >= 0.16       && < 0.20
     , text                            >= 1.1        && < 1.3
     , transformers                    >= 0.3        && < 0.6
+
+  default-language:
+    Haskell2010
diff --git a/src/Hedgehog.hs b/src/Hedgehog.hs
--- a/src/Hedgehog.hs
+++ b/src/Hedgehog.hs
@@ -108,6 +108,7 @@
   , tripping
 
   , eval
+  , evalNF
   , evalM
   , evalIO
   , evalEither
@@ -164,7 +165,7 @@
 import           Hedgehog.Internal.Property (classify, cover)
 import           Hedgehog.Internal.Property (discard, failure, success)
 import           Hedgehog.Internal.Property (DiscardLimit, withDiscards)
-import           Hedgehog.Internal.Property (eval, evalM, evalIO)
+import           Hedgehog.Internal.Property (eval, evalNF, evalM, evalIO)
 import           Hedgehog.Internal.Property (evalEither, evalExceptT)
 import           Hedgehog.Internal.Property (footnote, footnoteShow)
 import           Hedgehog.Internal.Property (forAll, forAllWith)
diff --git a/src/Hedgehog/Gen.hs b/src/Hedgehog/Gen.hs
--- a/src/Hedgehog/Gen.hs
+++ b/src/Hedgehog/Gen.hs
@@ -67,11 +67,16 @@
   -- ** Conditional
   , discard
   , filter
+  , filterT
   , mapMaybe
+  , mapMaybeT
   , just
+  , justT
 
   -- ** Collections
   , maybe
+  , either
+  , either_
   , list
   , seq
   , nonEmpty
@@ -106,4 +111,4 @@
 import           Hedgehog.Internal.Gen
 import           Hedgehog.Internal.State (sequential, parallel)
 
-import           Prelude hiding (filter, print, maybe, map, seq)
+import           Prelude hiding (either, filter, print, maybe, map, seq)
diff --git a/src/Hedgehog/Internal/Discovery.hs b/src/Hedgehog/Internal/Discovery.hs
--- a/src/Hedgehog/Internal/Discovery.hs
+++ b/src/Hedgehog/Internal/Discovery.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE CPP #-}
 module Hedgehog.Internal.Discovery (
     PropertySource(..)
   , readProperties
@@ -20,10 +21,13 @@
 import           Data.Map (Map)
 import qualified Data.Map as Map
 import qualified Data.Ord as Ord
-import           Data.Semigroup (Semigroup(..))
 
 import           Hedgehog.Internal.Property (PropertyName(..))
 import           Hedgehog.Internal.Source (LineNo(..), ColumnNo(..))
+
+#if __GLASGOW_HASKELL__ < 808
+import           Data.Semigroup (Semigroup(..))
+#endif
 
 ------------------------------------------------------------------------
 -- Property Extraction
diff --git a/src/Hedgehog/Internal/Distributive.hs b/src/Hedgehog/Internal/Distributive.hs
--- a/src/Hedgehog/Internal/Distributive.hs
+++ b/src/Hedgehog/Internal/Distributive.hs
@@ -1,5 +1,4 @@
 {-# OPTIONS_HADDOCK not-home #-}
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE InstanceSigs #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE ScopedTypeVariables #-}
diff --git a/src/Hedgehog/Internal/Gen.hs b/src/Hedgehog/Internal/Gen.hs
--- a/src/Hedgehog/Internal/Gen.hs
+++ b/src/Hedgehog/Internal/Gen.hs
@@ -12,6 +12,7 @@
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE StandaloneDeriving #-}
@@ -21,6 +22,7 @@
 #if __GLASGOW_HASKELL__ >= 806
 {-# LANGUAGE DerivingVia #-}
 #endif
+
 module Hedgehog.Internal.Gen (
   -- * Transformer
     Gen
@@ -107,6 +109,8 @@
 
   -- ** Collections
   , maybe
+  , either
+  , either_
   , list
   , seq
   , nonEmpty
@@ -174,8 +178,6 @@
 import           Control.Monad.Trans.Control (MonadBaseControl(..))
 import           Control.Monad.Catch (MonadThrow(..), MonadCatch(..))
 import           Control.Monad.Error.Class (MonadError(..))
-import           Control.Monad.Fail (MonadFail (..))
-import qualified Control.Monad.Fail as Fail
 import           Control.Monad.IO.Class (MonadIO(..))
 import           Control.Monad.Morph (MFunctor(..), MMonad(..))
 import qualified Control.Monad.Morph as Morph
@@ -199,9 +201,6 @@
 import           Data.ByteString (ByteString)
 import qualified Data.ByteString as ByteString
 import qualified Data.Char as Char
-#if __GLASGOW_HASKELL__ < 806
-import           Data.Coerce (coerce)
-#endif
 import           Data.Foldable (for_, toList)
 import           Data.Functor.Identity (Identity(..))
 import           Data.Int (Int8, Int16, Int32, Int64)
@@ -210,7 +209,6 @@
 import           Data.Map (Map)
 import qualified Data.Map as Map
 import qualified Data.Maybe as Maybe
-import           Data.Semigroup (Semigroup)
 import qualified Data.Semigroup as Semigroup
 import           Data.Sequence (Seq)
 import qualified Data.Sequence as Seq
@@ -221,6 +219,7 @@
 import           Data.Word (Word8, Word16, Word32, Word64)
 
 import           Hedgehog.Internal.Distributive (MonadTransDistributive(..))
+import           Hedgehog.Internal.Prelude hiding (either, maybe, seq)
 import           Hedgehog.Internal.Seed (Seed)
 import qualified Hedgehog.Internal.Seed as Seed
 import qualified Hedgehog.Internal.Shrink as Shrink
@@ -229,8 +228,12 @@
 import           Hedgehog.Range (Size, Range)
 import qualified Hedgehog.Range as Range
 
-import           Prelude hiding (filter, print, maybe, map, seq)
-
+#if __GLASGOW_HASKELL__ < 808
+import qualified Control.Monad.Fail as Fail
+#endif
+#if __GLASGOW_HASKELL__ < 806
+import           Data.Coerce (coerce)
+#endif
 
 ------------------------------------------------------------------------
 -- Generator transformer
@@ -517,8 +520,7 @@
           runGenT size sk . k =<<
           runGenT size sm m
 
-#if MIN_VERSION_base(4,13,0)
-#else
+#if __GLASGOW_HASKELL__ < 808
   fail =
     Fail.fail
 #endif
@@ -666,12 +668,12 @@
     lift . writer
   tell =
     lift . tell
-  listen =
-    undefined
-    --mapGenT listen
-  pass =
-    undefined
-    --mapGenT pass
+  listen m =
+    GenT $ \size seed ->
+      listen $ runGenT size seed m
+  pass m =
+    GenT $ \size seed ->
+      pass $ runGenT size seed m
 
 instance MonadError e m => MonadError e (GenT m) where
   throwError =
@@ -1353,6 +1355,29 @@
         (2, pure Nothing)
       , (1 + fromIntegral n, Just <$> gen)
       ]
+
+-- | Generates either an 'a' or a 'b'.
+--
+--   As the size grows, this generator generates @Right@s more often than @Left@s.
+--
+either :: MonadGen m => m a -> m b -> m (Either a b)
+either genA genB =
+  sized $ \n ->
+    frequency [
+        (2, Left <$> genA)
+      , (1 + fromIntegral n, Right <$> genB)
+      ]
+
+-- | Generates either an 'a' or a 'b', without bias.
+--
+--   This generator generates as many @Right@s as it does @Left@s.
+--
+either_ :: MonadGen m => m a -> m b -> m (Either a b)
+either_ genA genB =
+    choice [
+      Left <$> genA
+    , Right <$> genB
+    ]
 
 -- | Generates a list using a 'Range' to determine the length.
 --
diff --git a/src/Hedgehog/Internal/Prelude.hs b/src/Hedgehog/Internal/Prelude.hs
new file mode 100644
--- /dev/null
+++ b/src/Hedgehog/Internal/Prelude.hs
@@ -0,0 +1,17 @@
+{-# OPTIONS_GHC -fno-warn-duplicate-exports #-}
+{-# OPTIONS_GHC -fno-warn-unused-imports #-}
+{-# LANGUAGE NoImplicitPrelude #-}
+
+-- | Mostly for compatibility across different base Prelude changes.
+--
+module Hedgehog.Internal.Prelude (
+    Semigroup(..)
+  , MonadFail
+  , module Prelude
+  ) where
+
+import           Control.Monad.Fail (MonadFail)
+
+import           Data.Semigroup (Semigroup(..))
+
+import           Prelude hiding (filter, print, map)
diff --git a/src/Hedgehog/Internal/Property.hs b/src/Hedgehog/Internal/Property.hs
--- a/src/Hedgehog/Internal/Property.hs
+++ b/src/Hedgehog/Internal/Property.hs
@@ -12,6 +12,7 @@
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE RankNTypes #-}
 {-# LANGUAGE RecordWildCards #-}
 {-# LANGUAGE ScopedTypeVariables #-}
@@ -20,6 +21,7 @@
 {-# LANGUAGE TupleSections #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE UndecidableInstances #-} -- Distributive
+
 module Hedgehog.Internal.Property (
   -- * Property
     Property(..)
@@ -71,6 +73,7 @@
   , (/==)
 
   , eval
+  , evalNF
   , evalM
   , evalIO
   , evalEither
@@ -122,12 +125,12 @@
   ) where
 
 import           Control.Applicative (Alternative(..))
+import           Control.DeepSeq (NFData, rnf)
 import           Control.Monad (MonadPlus(..))
 import           Control.Monad.Base (MonadBase(..))
 import           Control.Monad.Catch (MonadThrow(..), MonadCatch(..))
 import           Control.Monad.Catch (SomeException(..), displayException)
 import           Control.Monad.Error.Class (MonadError(..))
-import           Control.Monad.Fail (MonadFail (..))
 import qualified Control.Monad.Fail as Fail
 import           Control.Monad.IO.Class (MonadIO(..))
 import           Control.Monad.Morph (MFunctor(..))
@@ -152,13 +155,13 @@
 import qualified Control.Monad.Trans.Writer.Strict as Strict
 
 import qualified Data.Char as Char
+import           Data.Functor (($>))
 import           Data.Functor.Identity (Identity(..))
 import           Data.Int (Int64)
 import           Data.Map (Map)
 import qualified Data.Map.Strict as Map
 import           Data.Number.Erf (invnormcdf)
 import qualified Data.List as List
-import           Data.Semigroup (Semigroup(..))
 import           Data.String (IsString)
 import           Data.Ratio ((%))
 import           Data.Typeable (typeOf)
@@ -167,11 +170,13 @@
 import           Hedgehog.Internal.Exception
 import           Hedgehog.Internal.Gen (Gen, GenT)
 import qualified Hedgehog.Internal.Gen as Gen
+import           Hedgehog.Internal.Prelude
 import           Hedgehog.Internal.Show
 import           Hedgehog.Internal.Source
 
 import           Language.Haskell.TH.Syntax (Lift)
 
+
 ------------------------------------------------------------------------
 
 -- | A property test, along with some configurable limits like how many times
@@ -700,9 +705,17 @@
 --   message.
 --
 failException :: (MonadTest m, HasCallStack) => SomeException -> m a
-failException (SomeException x) =
+failException x =
   withFrozenCallStack $
-    failWith Nothing $ unlines [
+    failExceptionWith [] x
+
+-- | Fails with an error which renders the given messages, the type of an exception,
+--   and its error message.
+--
+failExceptionWith :: (MonadTest m, HasCallStack) => [String] -> SomeException -> m a
+failExceptionWith messages (SomeException x) =
+  withFrozenCallStack
+    failWith Nothing $ unlines $ messages <> [
         "━━━ Exception (" ++ show (typeOf x) ++ ") ━━━"
       , List.dropWhileEnd Char.isSpace (displayException x)
       ]
@@ -779,6 +792,17 @@
 eval x =
   either (withFrozenCallStack failException) pure (tryEvaluate x)
 
+-- | Fails the test if the value throws an exception when evaluated to
+--   normal form (NF).
+--
+evalNF :: (MonadTest m, NFData a, HasCallStack) => a -> m a
+evalNF x =
+  let
+    messages =
+      ["━━━ Value could not be evaluated to normal form ━━━"]
+  in
+    either (withFrozenCallStack (failExceptionWith messages)) pure (tryEvaluate (rnf x)) $> x
+
 -- | Fails the test if the action throws an exception.
 --
 --   /The benefit of using this over simply letting the exception bubble up is/
@@ -1107,7 +1131,7 @@
 
 coverageFailures :: TestCount -> Coverage CoverCount -> [Label CoverCount]
 coverageFailures tests (Coverage kvs) =
-  filter (not . labelCovered tests) (Map.elems kvs)
+  List.filter (not . labelCovered tests) (Map.elems kvs)
 
 -- | Is true when the test coverage satisfies the specified 'Confidence'
 --   contstraint for all 'Coverage CoverCount's
diff --git a/src/Hedgehog/Internal/Report.hs b/src/Hedgehog/Internal/Report.hs
--- a/src/Hedgehog/Internal/Report.hs
+++ b/src/Hedgehog/Internal/Report.hs
@@ -6,6 +6,7 @@
 {-# LANGUAGE DoAndIfThenElse #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TupleSections #-}
 
@@ -45,14 +46,14 @@
 import           Data.Map (Map)
 import qualified Data.Map as Map
 import           Data.Maybe (mapMaybe, catMaybes)
-import           Data.Semigroup (Semigroup(..))
 import           Data.Traversable (for)
 
 import           Hedgehog.Internal.Config
 import           Hedgehog.Internal.Discovery (Pos(..), Position(..))
 import qualified Hedgehog.Internal.Discovery as Discovery
-import           Hedgehog.Internal.Property (Coverage(..), Label(..), LabelName(..))
+import           Hedgehog.Internal.Prelude
 import           Hedgehog.Internal.Property (CoverCount(..), CoverPercentage(..))
+import           Hedgehog.Internal.Property (Coverage(..), Label(..), LabelName(..))
 import           Hedgehog.Internal.Property (PropertyName(..), Log(..), Diff(..))
 import           Hedgehog.Internal.Property (ShrinkCount(..), PropertyCount(..))
 import           Hedgehog.Internal.Property (TestCount(..), DiscardCount(..))
@@ -608,25 +609,34 @@
 
 ppFailureReport :: MonadIO m => Maybe PropertyName -> TestCount -> FailureReport -> m [Doc Markup]
 ppFailureReport name tests (FailureReport size seed _ mcoverage inputs0 mlocation0 msg mdiff msgs0) = do
+  let
+    basic =
+      -- Move the failure message to the end section if we have
+      -- no source location or can't find the source file.
+      let
+        msgs1 =
+          msgs0 ++
+          (if null msg then [] else [msg])
+
+        docs =
+          concatMap ppTextLines msgs1 ++
+          maybe [] ppDiff mdiff
+      in
+        (docs, Nothing)
+
   (msgs1, mlocation) <-
     case mlocation0 of
       Nothing ->
-        -- Move the failure message to the end section if we have
-        -- no source location.
-        let
-          msgs1 =
-            msgs0 ++
-            (if null msg then [] else [msg])
-
-          docs =
-            concatMap ppTextLines msgs1 ++
-            maybe [] ppDiff mdiff
-        in
-          pure (docs, Nothing)
+        return basic
 
-      Just location0 ->
-        fmap (concatMap ppTextLines msgs0,) $
+      Just location0 -> do
+        mAdvanced <-
           ppFailureLocation (fmap WL.text $ List.lines msg) mdiff location0
+        case mAdvanced of
+          Just advanced ->
+            return (concatMap ppTextLines msgs0, Just advanced)
+          Nothing ->
+            return basic
 
   coverageLocations <-
     case mcoverage of
@@ -678,7 +688,7 @@
     WL.punctuate WL.line .
     fmap (WL.vsep . fmap (WL.indent 2)) .
     fmap (id :: [Doc Markup] -> [Doc Markup]) .
-    filter (not . null) $
+    List.filter (not . null) $
     concat [
       with args $
         WL.punctuate WL.line
diff --git a/src/Hedgehog/Internal/Runner.hs b/src/Hedgehog/Internal/Runner.hs
--- a/src/Hedgehog/Internal/Runner.hs
+++ b/src/Hedgehog/Internal/Runner.hs
@@ -5,8 +5,10 @@
 {-# LANGUAGE DoAndIfThenElse #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TemplateHaskell #-}
+
 module Hedgehog.Internal.Runner (
   -- * Running Individual Properties
     check
@@ -29,20 +31,19 @@
 import           Control.Monad.Catch (MonadCatch(..), catchAll)
 import           Control.Monad.IO.Class (MonadIO(..))
 
-import           Data.Semigroup ((<>))
-
 import           Hedgehog.Internal.Config
 import           Hedgehog.Internal.Gen (evalGenT)
+import           Hedgehog.Internal.Prelude
 import           Hedgehog.Internal.Property (DiscardCount(..), ShrinkCount(..))
 import           Hedgehog.Internal.Property (Group(..), GroupName(..))
 import           Hedgehog.Internal.Property (Journal(..), Coverage(..), CoverCount(..))
 import           Hedgehog.Internal.Property (Property(..), PropertyConfig(..), PropertyName(..))
 import           Hedgehog.Internal.Property (PropertyT(..), Failure(..), runTestT)
 import           Hedgehog.Internal.Property (ShrinkLimit, ShrinkRetries, withTests)
-import           Hedgehog.Internal.Property (TestCount(..), PropertyCount(..))
 import           Hedgehog.Internal.Property (TerminationCriteria(..))
-import           Hedgehog.Internal.Property (coverageSuccess, journalCoverage)
+import           Hedgehog.Internal.Property (TestCount(..), PropertyCount(..))
 import           Hedgehog.Internal.Property (confidenceSuccess, confidenceFailure)
+import           Hedgehog.Internal.Property (coverageSuccess, journalCoverage)
 import           Hedgehog.Internal.Property (defaultMinTests)
 import           Hedgehog.Internal.Queue
 import           Hedgehog.Internal.Region
diff --git a/src/Hedgehog/Internal/Source.hs b/src/Hedgehog/Internal/Source.hs
--- a/src/Hedgehog/Internal/Source.hs
+++ b/src/Hedgehog/Internal/Source.hs
@@ -1,6 +1,5 @@
 {-# OPTIONS_HADDOCK not-home #-}
 {-# LANGUAGE ConstraintKinds #-}
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE KindSignatures #-}
 {-# LANGUAGE RankNTypes #-}
diff --git a/src/Hedgehog/Internal/State.hs b/src/Hedgehog/Internal/State.hs
--- a/src/Hedgehog/Internal/State.hs
+++ b/src/Hedgehog/Internal/State.hs
@@ -1,5 +1,4 @@
 {-# OPTIONS_HADDOCK not-home #-}
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE DeriveFoldable #-}
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE DeriveTraversable #-}
diff --git a/src/Hedgehog/Internal/Tree.hs b/src/Hedgehog/Internal/Tree.hs
--- a/src/Hedgehog/Internal/Tree.hs
+++ b/src/Hedgehog/Internal/Tree.hs
@@ -11,6 +11,9 @@
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE UndecidableInstances #-} -- MonadBase
+#if __GLASGOW_HASKELL__ < 802
+{-# OPTIONS_GHC -fno-warn-incomplete-patterns #-}
+#endif
 module Hedgehog.Internal.Tree (
     Tree
   , pattern Tree
@@ -86,7 +89,9 @@
 pattern Tree :: NodeT Identity a -> Tree a
 pattern Tree node =
   TreeT (Identity node)
+#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE Tree #-}
+#endif
 
 -- | An effectful tree, each node in the tree can have an effect before it is
 --   produced.
@@ -105,7 +110,9 @@
 --
 type Node =
   NodeT Identity
+#if __GLASGOW_HASKELL__ >= 802
 {-# COMPLETE Node #-}
+#endif
 
 -- | Pattern to ease construction / deconstruction of pure nodes.
 --
@@ -330,12 +337,31 @@
   in
     go (List.inits xs0) xs0
 
-dropOne :: Monad m => [NodeT m a] -> [TreeT m [a]]
-dropOne ts = do
-  (xs, _y, zs) <- splits ts
-  pure . TreeT . pure $
-    interleave (xs ++ zs)
+-- | @removes n@ computes all ways we can remove chunks of size @n@ from a list
+--
+-- Examples
+--
+-- > removes 1 [1..3] == [[2,3],[1,3],[1,2]]
+-- > removes 2 [1..4] == [[3,4],[1,2]]
+-- > removes 2 [1..5] == [[3,4,5],[1,2,5],[1,2,3,4]]
+-- > removes 3 [1..5] == [[4,5],[1,2,3]]
+--
+-- Note that the last chunk we delete might have fewer elements than @n@.
+removes :: forall a. Int -> [a] -> [[a]]
+removes k = \xs -> go xs
+  where
+    go :: [a] -> [[a]]
+    go [] = []
+    go xs = xs2 : map (xs1 ++) (go xs2)
+      where
+        (xs1, xs2) = splitAt k xs
 
+dropSome :: Monad m => [NodeT m a] -> [TreeT m [a]]
+dropSome ts = do
+  n   <- takeWhile (> 0) $ iterate (`div` 2) (length ts)
+  ts' <- removes n ts
+  pure . TreeT . pure $ interleave ts'
+
 shrinkOne :: Monad m => [NodeT m a] -> [TreeT m [a]]
 shrinkOne ts = do
   (xs, y0, zs) <- splits ts
@@ -349,7 +375,7 @@
 interleave ts =
   NodeT (fmap nodeValue ts) $
     concat [
-        dropOne ts
+        dropSome ts
       , shrinkOne ts
       ]
 
diff --git a/src/Hedgehog/Main.hs b/src/Hedgehog/Main.hs
--- a/src/Hedgehog/Main.hs
+++ b/src/Hedgehog/Main.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 module Hedgehog.Main (
   -- * Running tests
     defaultMain