diff --git a/bench/Main.hs b/bench/Main.hs
--- a/bench/Main.hs
+++ b/bench/Main.hs
@@ -4,7 +4,6 @@
 
 import Criterion.Main
 import Data.Bits.Pdep
-import Data.Monoid ((<>))
 import Data.Word
 import HaskellWorks.Data.RankSelect.Base
 import HaskellWorks.Data.RankSelect.Base.Internal
diff --git a/doctest/DoctestDriver.hs b/doctest/DoctestDriver.hs
new file mode 100644
--- /dev/null
+++ b/doctest/DoctestDriver.hs
@@ -0,0 +1,12 @@
+{-# LANGUAGE CPP #-}
+
+#if MIN_VERSION_GLASGOW_HASKELL(8,4,4,0)
+{-# OPTIONS_GHC -F -pgmF doctest-discover #-}
+#else
+module Main where
+
+import qualified System.IO as IO
+
+main :: IO ()
+main = IO.putStrLn "WARNING: doctest will not run on GHC versions earlier than 8.4.4"
+#endif
diff --git a/hw-rankselect-base.cabal b/hw-rankselect-base.cabal
--- a/hw-rankselect-base.cabal
+++ b/hw-rankselect-base.cabal
@@ -1,7 +1,7 @@
 cabal-version: 2.2
 
 name:                   hw-rankselect-base
-version:                0.3.3.0
+version:                0.3.4.0
 synopsis:               Rank-select base
 description:            Please see README.md
 category:               Data, Bit, Succinct Data Structures, Data Structures
@@ -9,10 +9,10 @@
 bug-reports:            https://github.com/haskell-works/hw-rankselect-base/issues
 author:                 John Ky
 maintainer:             newhoggy@gmail.com
-copyright:              2016-2019 John Ky
+copyright:              2016-2020 John Ky
 license:                BSD-3-Clause
 license-file:           LICENSE
-tested-with:            GHC == 8.8.1, GHC == 8.6.5, GHC == 8.4.4, GHC == 8.2.2
+tested-with:            GHC == 8.10.1, GHC == 8.8.3, GHC == 8.6.5, GHC == 8.4.4
 build-type:             Simple
 extra-source-files:     README.md
 
@@ -25,29 +25,34 @@
   manual: False
   default: False
 
-common base                           { build-depends: base                           >= 4.8        && < 5      }
+common base                       { build-depends: base                       >= 4.11       && < 5      }
 
-common QuickCheck                     { build-depends: QuickCheck                     >= 2.10       && < 2.14   }
-common bits-extra                     { build-depends: bits-extra                     >= 0.0.0.4    && < 0.1    }
-common bitvec                         { build-depends: bitvec                         >= 1.0        && < 1.1    }
-common criterion                      { build-depends: criterion                      >= 1.2        && < 1.6    }
-common hedgehog                       { build-depends: hedgehog                       >= 0.6        && < 1.1    }
-common hspec                          { build-depends: hspec                          >= 2.2        && < 3      }
-common hw-bits                        { build-depends: hw-bits                        >= 0.7.1.0    && < 0.8    }
-common hw-hedgehog                    { build-depends: hw-hedgehog                    >= 0.1        && < 0.2    }
-common hw-hspec-hedgehog              { build-depends: hw-hspec-hedgehog              >= 0.1        && < 0.2    }
-common hw-int                         { build-depends: hw-int                         >= 0.0.0.1    && < 0.1    }
-common hw-prim                        { build-depends: hw-prim                        >= 0.5.0.5    && < 0.7    }
-common hw-string-parse                { build-depends: hw-string-parse                >= 0.0.0.2    && < 0.1    }
-common vector                         { build-depends: vector                         >= 0.12       && < 0.13   }
+common QuickCheck                 { build-depends: QuickCheck                 >= 2.10       && < 2.15   }
+common bits-extra                 { build-depends: bits-extra                 >= 0.0.0.4    && < 0.1    }
+common bitvec                     { build-depends: bitvec                     >= 1.0        && < 1.1    }
+common criterion                  { build-depends: criterion                  >= 1.2        && < 1.6    }
+common doctest                    { build-depends: doctest                    >= 0.16.2     && < 0.17   }
+common doctest-discover           { build-depends: doctest-discover           >= 0.2        && < 0.3    }
+common hedgehog                   { build-depends: hedgehog                   >= 0.6        && < 1.1    }
+common hspec                      { build-depends: hspec                      >= 2.2        && < 3      }
+common hw-bits                    { build-depends: hw-bits                    >= 0.7.1.0    && < 0.8    }
+common hw-hedgehog                { build-depends: hw-hedgehog                >= 0.1        && < 0.2    }
+common hw-hspec-hedgehog          { build-depends: hw-hspec-hedgehog          >= 0.1        && < 0.2    }
+common hw-int                     { build-depends: hw-int                     >= 0.0.0.1    && < 0.1    }
+common hw-prim                    { build-depends: hw-prim                    >= 0.5.0.5    && < 0.7    }
+common hw-string-parse            { build-depends: hw-string-parse            >= 0.0.0.2    && < 0.1    }
+common vector                     { build-depends: vector                     >= 0.12       && < 0.13   }
 
 common config
   default-language:     Haskell2010
   ghc-options:          -Wall -fwarn-tabs -fwarn-incomplete-uni-patterns -fwarn-incomplete-record-updates -O2 -msse4.2
   if (flag(bmi2)) && (impl(ghc >=8.4.1))
-    ghc-options: -mbmi2 -msse4.2
-    cpp-options: -DBMI2_ENABLED
+    ghc-options:        -mbmi2 -msse4.2
+    cpp-options:        -DBMI2_ENABLED
 
+common hw-rankselect-base
+  build-depends:        hw-rankselect-base
+
 library
   import:               base, config
                       , bits-extra
@@ -88,8 +93,6 @@
                         HaskellWorks.Data.RankSelect.Base.Rank1Spec
                         HaskellWorks.Data.RankSelect.Base.Select0Spec
                         HaskellWorks.Data.RankSelect.Base.Select1Spec
-                        Paths_hw_rankselect_base
-  autogen-modules:      Paths_hw_rankselect_base
   hs-source-dirs:       test
   ghc-options:          -threaded -rtsopts -with-rtsopts=-N
   build-depends:        hw-rankselect-base
@@ -104,7 +107,16 @@
                       , vector
   type:                 exitcode-stdio-1.0
   main-is:              Main.hs
-  other-modules:        Paths_hw_rankselect_base
-  autogen-modules:      Paths_hw_rankselect_base
   hs-source-dirs:       bench
   build-depends:        hw-rankselect-base
+
+test-suite doctest
+  import:               base, config
+                      , doctest
+                      , doctest-discover
+                      , hw-rankselect-base
+  type:                 exitcode-stdio-1.0
+  ghc-options:          -threaded
+  main-is:              DoctestDriver.hs
+  HS-Source-Dirs:       doctest
+  build-tool-depends:   doctest-discover:doctest-discover
diff --git a/src/HaskellWorks/Data/RankSelect/Base/Rank0.hs b/src/HaskellWorks/Data/RankSelect/Base/Rank0.hs
--- a/src/HaskellWorks/Data/RankSelect/Base/Rank0.hs
+++ b/src/HaskellWorks/Data/RankSelect/Base/Rank0.hs
@@ -21,7 +21,7 @@
 import qualified Data.Vector.Storable as DVS
 import qualified Data.Vector.Unboxed  as DVU
 
-{-# ANN module ("HLint: Ignore Reduce duplication"  :: String) #-}
+{-# ANN module ("HLint: ignore Reduce duplication"  :: String) #-}
 
 class Rank0 v where
   rank0 :: v -> Count -> Count
diff --git a/src/HaskellWorks/Data/RankSelect/Base/Rank1.hs b/src/HaskellWorks/Data/RankSelect/Base/Rank1.hs
--- a/src/HaskellWorks/Data/RankSelect/Base/Rank1.hs
+++ b/src/HaskellWorks/Data/RankSelect/Base/Rank1.hs
@@ -21,7 +21,7 @@
 import qualified Data.Vector.Storable as DVS
 import qualified Data.Vector.Unboxed  as DVU
 
-{-# ANN module ("HLint: Ignore Reduce duplication"  :: String) #-}
+{-# ANN module ("HLint: ignore Reduce duplication"  :: String) #-}
 
 class Rank1 v where
   rank1 :: v -> Count -> Count
