diff --git a/app/App/Commands.hs b/app/App/Commands.hs
--- a/app/App/Commands.hs
+++ b/app/App/Commands.hs
@@ -2,7 +2,6 @@
 
 import App.Commands.Capabilities
 import App.Commands.CreateIndex
-import Data.Semigroup            ((<>))
 import Options.Applicative
 
 commands :: Parser (IO ())
diff --git a/app/App/Commands/Capabilities.hs b/app/App/Commands/Capabilities.hs
--- a/app/App/Commands/Capabilities.hs
+++ b/app/App/Commands/Capabilities.hs
@@ -4,7 +4,6 @@
   ( cmdCapabilities
   ) where
 
-import Data.Semigroup                             ((<>))
 import HaskellWorks.Data.Json.Simd.Index.Simple
 import HaskellWorks.Data.Json.Simd.Index.Standard
 import Options.Applicative                        hiding (columns)
@@ -15,7 +14,7 @@
 {-# ANN module ("HLint: ignore Redundant do"        :: String) #-}
 
 runCapabilities :: () -> IO ()
-runCapabilities opts = do
+runCapabilities _ = do
   IO.putStrLn "Capabalities:"
   IO.putStrLn $ "  standard indexing: " <> show enabledMakeStandardJsonIbBps
   IO.putStrLn $ "  simple indexing: "   <> show enabledMakeSimpleJsonIbBps
diff --git a/app/App/Commands/CreateIndex.hs b/app/App/Commands/CreateIndex.hs
--- a/app/App/Commands/CreateIndex.hs
+++ b/app/App/Commands/CreateIndex.hs
@@ -9,7 +9,6 @@
 import Control.Lens
 import Control.Monad
 import Data.Maybe
-import Data.Semigroup                             ((<>))
 import HaskellWorks.Data.Json.Simd.Index.Simple
 import HaskellWorks.Data.Json.Simd.Index.Standard
 import Options.Applicative                        hiding (columns)
diff --git a/app/Main.hs b/app/Main.hs
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -2,7 +2,6 @@
 
 import App.Commands
 import Control.Monad
-import Data.Semigroup      ((<>))
 import Options.Applicative
 
 main :: IO ()
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-json-simd.cabal b/hw-json-simd.cabal
--- a/hw-json-simd.cabal
+++ b/hw-json-simd.cabal
@@ -1,7 +1,7 @@
-cabal-version:  2.2
+cabal-version: 2.2
 
 name:                   hw-json-simd
-version:                0.1.0.4
+version:                0.1.1.0
 synopsis:               SIMD-based JSON semi-indexer
 description:            Please see the README on GitHub at <https://github.com/haskell-works/hw-json-simd#readme>
 category:               Data
@@ -9,11 +9,11 @@
 bug-reports:            https://github.com/haskell-works/hw-json-simd/issues
 author:                 John Ky
 maintainer:             newhoggy@gmail.com
-copyright:              2018-2019 John Ky
+copyright:              2018-2020 John Ky
 license:                BSD-3-Clause
 license-file:           LICENSE
 build-type:             Simple
-tested-with:            GHC == 8.8.1, GHC == 8.6.3, 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
 extra-source-files:     cbits/debug.h
                         cbits/simd.h
                         cbits/intrinsics.h
@@ -44,16 +44,20 @@
   manual: False
   default: True
 
-common base                   { build-depends: base                 >= 4          && < 5      }
-common bytestring             { build-depends: bytestring           >= 0.10.6     && < 0.11   }
-common hw-prim                { build-depends: hw-prim              >= 0.6.2.35   && < 0.7    }
-common lens                   { build-depends: lens                 >= 4          && < 5      }
-common optparse-applicative   { build-depends: optparse-applicative >= 0.14       && < 0.16   }
-common vector                 { build-depends: vector               >= 0.12       && < 0.13   }
+common base                       { build-depends: base                       >= 4.11       && < 5      }
 
-common semigroups     { if (!impl(ghc >= 8.0.1))  { build-depends: { semigroups   >= 0.8.4  && < 0.19 } } }
-common transformers   { if (!impl(ghc >= 8.0.1))  { build-depends: { transformers >= 0.4    && < 0.6  } } }
+common bytestring                 { build-depends: bytestring                 >= 0.10.6     && < 0.11   }
+common doctest                    { build-depends: doctest                    >= 0.16.2     && < 0.17   }
+common doctest-discover           { build-depends: doctest-discover           >= 0.2        && < 0.3    }
+common hw-prim                    { build-depends: hw-prim                    >= 0.6.2.35   && < 0.7    }
+common lens                       { build-depends: lens                       >= 4          && < 5      }
+common optparse-applicative       { build-depends: optparse-applicative       >= 0.14       && < 0.16   }
+common transformers               { build-depends: transformers               >= 0.4        && < 0.6    }
+common vector                     { build-depends: vector                     >= 0.12       && < 0.13   }
 
+common hw-json-simd
+  build-depends:        hw-json-simd
+
 common config
   ghc-options:          -Wall
   default-language:     Haskell2010
@@ -101,10 +105,8 @@
                       , hw-prim
                       , lens
                       , optparse-applicative
-                      , semigroups
                       , vector
   main-is:              Main.hs
-  autogen-modules:      Paths_hw_json_simd
   hs-source-dirs:       app
   build-depends:        hw-json-simd
   ghc-options:          -threaded -rtsopts -with-rtsopts=-N
@@ -113,20 +115,28 @@
                         App.Commands.CreateIndex
                         App.Commands.Types
                         App.Lens
-                        Paths_hw_json_simd
 
 test-suite hw-json-simd-test
   import:               base, config
                       , bytestring
                       , hw-prim
                       , lens
-                      , semigroups
                       , transformers
                       , vector
   type:                 exitcode-stdio-1.0
   main-is:              Spec.hs
-  autogen-modules:      Paths_hw_json_simd
-  other-modules:        Paths_hw_json_simd
   hs-source-dirs:       test
   ghc-options:          -threaded -rtsopts -with-rtsopts=-N
   build-depends:        hw-json-simd
+
+test-suite doctest
+  import:               base, config
+                      , doctest
+                      , doctest-discover
+                      , hw-json-simd
+  default-language:     Haskell2010
+  type:                 exitcode-stdio-1.0
+  ghc-options:          -threaded
+  main-is:              DoctestDriver.hs
+  HS-Source-Dirs:       doctest
+  build-tool-depends:   doctest-discover:doctest-discover