diff --git a/.travis.yml b/.travis.yml
index 146465335..4b45fed5f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -22,9 +22,8 @@ install:
 - "./travis_long stack +RTS -N2 -RTS setup"
 - "./travis_long stack build --only-snapshot"
 - "./travis_long stack install ide-backend-server"
-- "export PATH=\"${HOME}/.local/bin\":${PATH}"
 script:
-- "./travis_long stack +RTS -N1 -RTS build"
+- "STACK_YAML=stack_test.yaml ./travis_long stack +RTS -N1 -RTS build --test --no-run-tests"
 - "./travis_long stack +RTS -N1 -RTS build --test"
 - "./travis_long stack exec emacs24 -- -q --batch -L elisp -l elisp/tests/hie-tests.el
   -f ert-run-tests-batch-and-exit"
diff --git a/Makefile b/Makefile
index 4c2887fdf..44141c766 100644
--- a/Makefile
+++ b/Makefile
@@ -5,16 +5,19 @@ ifeq (,$(shell which $(emacs) 2> /dev/null))
 endif
 
 .PHONY: test
-test: test-haskell test-emacs
+test: build-haskell test-haskell test-emacs
 
 .PHONY: test-emacs
 test-emacs:
 	stack exec $(emacs) -- -q --batch -L elisp -l elisp/tests/hie-tests.el -f ert-run-tests-batch-and-exit
 
 .PHONY: test-haskell
+build-haskell:
+	@STACK_YAML=stack_test.yaml stack build --test --no-run-tests
 test-haskell:
 	# stack build --test --pedantic
 	# stack complains about deprecations in ghc-mod as an extra dep
+# build with -Werror enabled but run the tests without it because ide-backend picks it up
 	stack build --test
 
 .PHONY: ghci-test
diff --git a/app/MainHie.hs b/app/MainHie.hs
index 1501f431e..10f676b50 100644
--- a/app/MainHie.hs
+++ b/app/MainHie.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
 {-# LANGUAGE GADTs #-}
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TemplateHaskell #-}
diff --git a/haskell-ide-engine.cabal b/haskell-ide-engine.cabal
index 369770d83..97b21a8b1 100644
--- a/haskell-ide-engine.cabal
+++ b/haskell-ide-engine.cabal
@@ -13,6 +13,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   hs-source-dirs:      src
   exposed-modules:     Haskell.Ide.Engine.BasePlugin
@@ -94,6 +98,8 @@ executable hie
                      , transformers
                      , vinyl
   ghc-options:         -threaded -rtsopts -with-rtsopts=-N -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
 
 test-suite haskell-ide-test
@@ -135,6 +141,8 @@ test-suite haskell-ide-test
                      , unordered-containers
                      , vinyl
   ghc-options:         -threaded -rtsopts -with-rtsopts=-N -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
 
 source-repository head
diff --git a/hie-apply-refact/Haskell/Ide/ApplyRefactPlugin.hs b/hie-apply-refact/Haskell/Ide/ApplyRefactPlugin.hs
index cb11afe4a..4230653d5 100644
--- a/hie-apply-refact/Haskell/Ide/ApplyRefactPlugin.hs
+++ b/hie-apply-refact/Haskell/Ide/ApplyRefactPlugin.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -17,8 +19,6 @@ import           Haskell.Ide.Engine.PluginUtils
 import           Haskell.Ide.Engine.SemanticTypes
 import           Language.Haskell.HLint3 as Hlint
 import           Refact.Apply
-import qualified Refact.Types as R
-import           Refact.Types hiding (SrcSpan)
 import           System.Directory
 import           System.IO.Extra
 
@@ -108,7 +108,7 @@ showParseError (Hlint.ParseError loc message content) = unlines [show loc, messa
 makeDiffResult :: FilePath -> T.Text -> IO HieDiff
 makeDiffResult orig new = do
   origText <- T.readFile orig
-  let (HieDiff f s d) = diffText (orig,origText) ("changed",new)
+  let (HieDiff f _ d) = diffText (orig,origText) ("changed",new)
   f' <- liftIO $ makeRelativeToCurrentDirectory f
   -- return (HieDiff f' s' d)
   return (HieDiff f' "changed" d)
diff --git a/hie-apply-refact/hie-apply-refact.cabal b/hie-apply-refact/hie-apply-refact.cabal
index 71de9505b..1ba118945 100644
--- a/hie-apply-refact/hie-apply-refact.cabal
+++ b/hie-apply-refact/hie-apply-refact.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:     Haskell.Ide.ApplyRefactPlugin
   build-depends:       base >= 4.7 && < 5
@@ -30,4 +34,6 @@ library
                      , transformers
                      , vinyl >= 0.5 && < 0.6
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/hie-base/hie-base.cabal b/hie-base/hie-base.cabal
index 8b9ad802b..531085c5c 100644
--- a/hie-base/hie-base.cabal
+++ b/hie-base/hie-base.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:
                        Haskell.Ide.Engine.PluginTypes
@@ -24,4 +28,6 @@ library
                      , singletons
                      , vinyl
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/hie-docs-generator/hie-docs-generator.cabal b/hie-docs-generator/hie-docs-generator.cabal
index b5b0c22fd..1d115a783 100644
--- a/hie-docs-generator/hie-docs-generator.cabal
+++ b/hie-docs-generator/hie-docs-generator.cabal
@@ -16,6 +16,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 executable hie-docs-generator
   main-is:             Main.hs
   other-modules:       Options, Examples
@@ -39,4 +43,7 @@ executable hie-docs-generator
                      , pcre-heavy
                      , text
   hs-source-dirs:      src
-  default-language:    Haskell2010
\ No newline at end of file
+  ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
+  default-language:    Haskell2010
diff --git a/hie-docs-generator/src/Examples.hs b/hie-docs-generator/src/Examples.hs
index 5e6156566..e39790c26 100644
--- a/hie-docs-generator/src/Examples.hs
+++ b/hie-docs-generator/src/Examples.hs
@@ -1,16 +1,10 @@
 {-# LANGUAGE OverloadedStrings #-}
 module Examples where
 
-import qualified Data.Aeson as A
-import qualified Data.ByteString.Lazy as BSL
 import qualified Data.Map as M
 import           Data.Monoid
-import qualified Data.Text as T
-import           Haskell.Ide.Engine.BasePlugin
-import           Haskell.Ide.HaRePlugin
 import           Haskell.Ide.Engine.PluginDescriptor
 import           Haskell.Ide.Engine.Transport.JsonStdio
-import           Options
 
 jsonStdioExample :: PluginId -> UntaggedCommandDescriptor -> WireRequest
 jsonStdioExample pluginId (CommandDesc{cmdName = name,cmdContexts = contexts,cmdAdditionalParams = cmdParams}) =
diff --git a/hie-docs-generator/src/Main.hs b/hie-docs-generator/src/Main.hs
index 2cccf6f9f..996b2bfb5 100644
--- a/hie-docs-generator/src/Main.hs
+++ b/hie-docs-generator/src/Main.hs
@@ -13,13 +13,7 @@ import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
 import qualified Data.Text.IO as T
 import           Examples
-import           Haskell.Ide.ApplyRefactPlugin
-import           Haskell.Ide.Engine.BasePlugin
 import           Haskell.Ide.Engine.PluginDescriptor
-import           Haskell.Ide.ExamplePlugin2
-import           Haskell.Ide.ExamplePluginAsync
-import           Haskell.Ide.GhcModPlugin
-import           Haskell.Ide.HaRePlugin
 import qualified Options as O
 import           Options.Applicative
 import           System.Directory
@@ -41,11 +35,11 @@ newtype DocGenM a =
 
 generateDocs :: DocGenM ()
 generateDocs =
-  do path <- pluginIndexPath
+  do indexPath <- pluginIndexPath
      index <- pluginIndex
      prefix <- asks O.prefix
      liftIO . createDirectoryIfMissing True $ prefix </> "plugins"
-     liftIO $ T.writeFile path index
+     liftIO $ T.writeFile indexPath index
      plugins <- asks O.plugins
      let pluginDocs = map pluginDoc $ M.toList plugins
      pluginDocPaths <- mapM pluginDocPath $ M.keys plugins
diff --git a/hie-eg-plugin-async/Haskell/Ide/ExamplePluginAsync.hs b/hie-eg-plugin-async/Haskell/Ide/ExamplePluginAsync.hs
index 210b1060c..e82274574 100644
--- a/hie-eg-plugin-async/Haskell/Ide/ExamplePluginAsync.hs
+++ b/hie-eg-plugin-async/Haskell/Ide/ExamplePluginAsync.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE GADTs #-}
@@ -8,13 +10,11 @@ import           Control.Concurrent
 import           Control.Concurrent.STM.TChan
 import           Control.Monad.IO.Class
 import           Control.Monad.STM
-import qualified Data.Map as Map
 import           Data.Monoid
 import qualified Data.Text as T
 import           Haskell.Ide.Engine.ExtensibleState
 import           Haskell.Ide.Engine.MonadFunctions
 import           Haskell.Ide.Engine.PluginDescriptor
-import           Haskell.Ide.Engine.PluginUtils
 
 -- ---------------------------------------------------------------------
 
@@ -64,7 +64,7 @@ instance ExtensionClass AsyncPluginState where
 
 -- | This command manages interaction with a separate process, doing stuff.
 longRunningCmdSync :: WorkerCmd -> CommandFunc T.Text
-longRunningCmdSync cmd = CmdSync $ \_ctx req -> do
+longRunningCmdSync cmd = CmdSync $ \_ctx _req -> do
   SubProcess cin cout _tid <- ensureProcessRunning
   liftIO $ atomically $ writeTChan cin cmd
   res <- liftIO $ atomically $ readTChan cout
@@ -95,6 +95,7 @@ ensureProcessRunning = do
 workerProc :: TChan WorkerCmd -> TChan T.Text -> IO ()
 workerProc cin cout = loop 1
   where
+    loop :: Integer -> IO ()
     loop cnt = do
       debugm "workerProc:top of loop"
       req <- liftIO $ atomically $ readTChan cin
@@ -111,7 +112,7 @@ workerProc cin cout = loop 1
 
 -- | This command manages interaction with a separate process, doing stuff.
 streamingCmdAsync :: WorkerCmdAsync -> CommandFunc T.Text
-streamingCmdAsync cmd = CmdAsync $ \replyFunc _ctx req -> do
+streamingCmdAsync cmd = CmdAsync $ \replyFunc _ctx _req -> do
   tid <- liftIO $ forkIO (workerProcAsync cmd replyFunc)
   debugm $ "streamingCmdAsync:launched worker as " ++ show tid
   let tidStr = T.pack (show tid ++ ":")
diff --git a/hie-eg-plugin-async/hie-eg-plugin-async.cabal b/hie-eg-plugin-async/hie-eg-plugin-async.cabal
index 4d529f8a2..63c0b2bd6 100644
--- a/hie-eg-plugin-async/hie-eg-plugin-async.cabal
+++ b/hie-eg-plugin-async/hie-eg-plugin-async.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:     Haskell.Ide.ExamplePluginAsync
   build-depends:       base >= 4.7 && < 5
@@ -21,4 +25,6 @@ library
                      , text
                      , transformers
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/hie-example-plugin2/Haskell/Ide/ExamplePlugin2.hs b/hie-example-plugin2/Haskell/Ide/ExamplePlugin2.hs
index fd13b5ae6..6825517b1 100644
--- a/hie-example-plugin2/Haskell/Ide/ExamplePlugin2.hs
+++ b/hie-example-plugin2/Haskell/Ide/ExamplePlugin2.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE OverloadedStrings #-}
diff --git a/hie-example-plugin2/hie-example-plugin2.cabal b/hie-example-plugin2/hie-example-plugin2.cabal
index 2f625c2e0..d12dc11cf 100644
--- a/hie-example-plugin2/hie-example-plugin2.cabal
+++ b/hie-example-plugin2/hie-example-plugin2.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:     Haskell.Ide.ExamplePlugin2
   build-depends:       base >= 4.7 && < 5
@@ -20,4 +24,6 @@ library
                      , text
                      , transformers
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/hie-ghc-mod/Haskell/Ide/GhcModPlugin.hs b/hie-ghc-mod/Haskell/Ide/GhcModPlugin.hs
index 4d9f24007..35b7189e1 100644
--- a/hie-ghc-mod/Haskell/Ide/GhcModPlugin.hs
+++ b/hie-ghc-mod/Haskell/Ide/GhcModPlugin.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
 {-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE FlexibleContexts #-}
@@ -8,7 +10,6 @@ module Haskell.Ide.GhcModPlugin where
 
 import           Haskell.Ide.Engine.PluginUtils
 
-import           Control.Exception
 import           Control.Monad.IO.Class
 import           Data.Aeson
 import           Data.Either
@@ -18,7 +19,6 @@ import qualified Data.Text.Read as T
 import           Data.Vinyl
 import qualified Exception as G
 import           Haskell.Ide.Engine.PluginDescriptor
-import           Haskell.Ide.Engine.PluginUtils
 import           Haskell.Ide.Engine.SemanticTypes
 import qualified Language.Haskell.GhcMod as GM
 import qualified Language.Haskell.GhcMod.Monad as GM
diff --git a/hie-ghc-mod/hie-ghc-mod.cabal b/hie-ghc-mod/hie-ghc-mod.cabal
index 14c169973..58adcb402 100644
--- a/hie-ghc-mod/hie-ghc-mod.cabal
+++ b/hie-ghc-mod/hie-ghc-mod.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:     Haskell.Ide.GhcModPlugin
   build-depends:       base >= 4.7 && < 5
@@ -27,4 +31,6 @@ library
                      , vinyl >= 0.5 && < 0.6
 
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/hie-hare/Haskell/Ide/HaRePlugin.hs b/hie-hare/Haskell/Ide/HaRePlugin.hs
index 4c725dfe0..78e472c71 100644
--- a/hie-hare/Haskell/Ide/HaRePlugin.hs
+++ b/hie-hare/Haskell/Ide/HaRePlugin.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
 {-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE OverloadedStrings #-}
@@ -143,10 +145,7 @@ makeRefactorResult changedFiles = do
     diffOne f1 = do
       let (baseFileName,ext) = splitExtension f1
           f2 = (baseFileName ++ ".refactored" ++ ext)
-      (HieDiff f s d) <- diffFiles f1 f2
-      f' <- liftIO $ makeRelativeToCurrentDirectory f
-      s' <- liftIO $ makeRelativeToCurrentDirectory s
-      return (HieDiff f s d)
+      diffFiles f1 f2
   diffs <- mapM diffOne changedFiles
   return (RefactorResult diffs)
 
diff --git a/hie-hare/hie-hare.cabal b/hie-hare/hie-hare.cabal
index 7682ea2f6..c7f9219f4 100644
--- a/hie-hare/hie-hare.cabal
+++ b/hie-hare/hie-hare.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:     Haskell.Ide.HaRePlugin
   build-depends:       base >= 4.7 && < 5
@@ -27,4 +31,6 @@ library
                      , transformers
                      , vinyl >= 0.5 && < 0.6
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/hie-ide-backend/hie-ide-backend.cabal b/hie-ide-backend/hie-ide-backend.cabal
index 9cc5065e7..b4c04f73f 100644
--- a/hie-ide-backend/hie-ide-backend.cabal
+++ b/hie-ide-backend/hie-ide-backend.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:     Haskell.Ide.IdeBackend
   build-depends:       aeson
@@ -28,4 +32,6 @@ library
                      , transformers
                      , vinyl
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/hie-plugin-api/Haskell/Ide/Engine/Monad.hs b/hie-plugin-api/Haskell/Ide/Engine/Monad.hs
index 3dada7452..4ca871454 100644
--- a/hie-plugin-api/Haskell/Ide/Engine/Monad.hs
+++ b/hie-plugin-api/Haskell/Ide/Engine/Monad.hs
@@ -5,19 +5,12 @@
 
 module Haskell.Ide.Engine.Monad where
 
-import           Control.Concurrent
-import           Control.Concurrent.MVar
 import           Control.Exception
 import           Control.Monad.IO.Class
 import           Control.Monad.State.Strict
-import           Data.Char
 import           Haskell.Ide.Engine.PluginDescriptor
 import qualified Language.Haskell.GhcMod.Monad as GM
 import qualified Language.Haskell.GhcMod.Types as GM
-import qualified Language.Haskell.GhcMod.Utils as GM
-import qualified Language.Haskell.GhcMod.Debug as GM
-import           System.Directory
-import           System.IO.Unsafe
 -- ---------------------------------------------------------------------
 
 runIdeM :: IdeState -> IdeM a -> IO a
diff --git a/hie-plugin-api/hie-plugin-api.cabal b/hie-plugin-api/hie-plugin-api.cabal
index a83761e3e..237786175 100644
--- a/hie-plugin-api/hie-plugin-api.cabal
+++ b/hie-plugin-api/hie-plugin-api.cabal
@@ -11,6 +11,10 @@ build-type:          Simple
 -- extra-source-files:
 cabal-version:       >=1.10
 
+flag pedantic
+  Description: Enable -Werror
+  Default:     False
+
 library
   exposed-modules:
                        Haskell.Ide.Engine.ExtensibleState
@@ -40,4 +44,6 @@ library
                      , unordered-containers
                      , vinyl >= 0.5 && < 0.6
   ghc-options:         -Wall
+  if flag(pedantic)
+     ghc-options:      -Werror
   default-language:    Haskell2010
diff --git a/src/Haskell/Ide/Engine/BasePlugin.hs b/src/Haskell/Ide/Engine/BasePlugin.hs
index 48cd38115..db90df819 100644
--- a/src/Haskell/Ide/Engine/BasePlugin.hs
+++ b/src/Haskell/Ide/Engine/BasePlugin.hs
@@ -1,3 +1,5 @@
+{-# OPTIONS_GHC -fno-warn-partial-type-signatures #-}
+
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE TemplateHaskell #-}
diff --git a/src/Haskell/Ide/Engine/Transport/JsonHttp.hs b/src/Haskell/Ide/Engine/Transport/JsonHttp.hs
index 212a25b88..55162da28 100644
--- a/src/Haskell/Ide/Engine/Transport/JsonHttp.hs
+++ b/src/Haskell/Ide/Engine/Transport/JsonHttp.hs
@@ -43,7 +43,8 @@ newtype Greet = Greet { _msg :: T.Text }
   deriving (Generic, Show)
 
 instance FromJSON Greet
-instance ToJSON Greet
+instance ToJSON Greet where
+  toJSON = genericToJSON defaultOptions
 
 newtype TaggedMap (tags :: [ParamDescType]) = TaggedMap ParamMap deriving (Monoid)
 
diff --git a/stack_test.yaml b/stack_test.yaml
new file mode 100644
index 000000000..889dea2e1
--- /dev/null
+++ b/stack_test.yaml
@@ -0,0 +1,42 @@
+resolver: nightly-2016-01-06
+packages:
+- .
+- hie-apply-refact
+- hie-base
+- hie-example-plugin2
+- hie-eg-plugin-async
+- hie-plugin-api
+- hie-ghc-mod
+- hie-hare
+- hie-docs-generator
+- hie-ide-backend
+- location:
+    git: https://github.com/kazu-yamamoto/ghc-mod.git
+    commit: b9bd4ebf77b22d2d9061d647d7799ddcc7c51228
+  extra-dep: true
+- location:
+    git: https://github.com/mpickering/apply-refact.git
+    commit: 402458652844c1a0f42b15123e0ceff761919415
+  extra-dep: true
+extra-deps: []
+flags:
+  haskell-ide-engine:
+    pedantic: true
+  hie-apply-refact:
+    pedantic: true
+  hie-base:
+    pedantic: true
+  hie-docs-generator:
+    pedantic: true
+  hie-eg-plugin-async:
+    pedantic: true
+  hie-example-plugin2:
+    pedantic: true
+  hie-ghc-mod:
+    pedantic: true
+  hie-hare:
+    pedantic: true
+  hie-ide-backend:
+    pedantic: true
+  hie-plugin-api:
+    pedantic: true
diff --git a/test/ApplyRefactPluginSpec.hs b/test/ApplyRefactPluginSpec.hs
index e2f302f52..8f18bba16 100644
--- a/test/ApplyRefactPluginSpec.hs
+++ b/test/ApplyRefactPluginSpec.hs
@@ -4,7 +4,6 @@ module ApplyRefactPluginSpec where
 import           Control.Concurrent.STM.TChan
 import           Control.Monad.STM
 import           Data.Aeson
-import           Data.Algorithm.Diff
 import qualified Data.Map as Map
 import           Haskell.Ide.Engine.Dispatcher
 import           Haskell.Ide.Engine.Monad
diff --git a/test/DispatcherSpec.hs b/test/DispatcherSpec.hs
index 5a13658b6..4cdc8da6d 100644
--- a/test/DispatcherSpec.hs
+++ b/test/DispatcherSpec.hs
@@ -12,8 +12,6 @@ import qualified Data.HashMap.Strict as H
 import qualified Data.HashMap.Strict as HM
 import qualified Data.Map as Map
 import qualified Data.Text as T
-import qualified Data.Vinyl.Functor as Vinyl
-import           GHC.TypeLits
 import           Haskell.Ide.Engine.Dispatcher
 import           Haskell.Ide.Engine.Monad
 import           Haskell.Ide.Engine.MonadFunctions
diff --git a/test/ExamplePluginAsyncSpec.hs b/test/ExamplePluginAsyncSpec.hs
index 3bafdea85..6c86c67fc 100644
--- a/test/ExamplePluginAsyncSpec.hs
+++ b/test/ExamplePluginAsyncSpec.hs
@@ -1,24 +1,16 @@
 {-# LANGUAGE OverloadedStrings #-}
 module ExamplePluginAsyncSpec where
 
-import           Control.Concurrent
 import           Control.Concurrent.STM.TChan
-import           Control.Monad.IO.Class
 import           Control.Monad.STM
 import           Data.Aeson
 import qualified Data.HashMap.Strict as H
-import qualified Data.Text as T
-import qualified Data.HashMap.Strict as HM
 import qualified Data.Map as Map
-import           Data.Typeable
 import           Haskell.Ide.Engine.Dispatcher
-import           Haskell.Ide.Engine.ExtensibleState
 import           Haskell.Ide.Engine.Monad
 import           Haskell.Ide.Engine.MonadFunctions
 import           Haskell.Ide.Engine.PluginDescriptor
 import           Haskell.Ide.Engine.Types
-import           Haskell.Ide.Engine.Utils
-import           Haskell.Ide.Engine.PluginDescriptor
 import           Haskell.Ide.ExamplePluginAsync
 
 import           Test.Hspec
@@ -35,7 +27,6 @@ examplePluginAsyncSpec = do
   describe "stores and retrieves in the state" $ do
     it "stores the first one" $ do
       chan <- atomically newTChan
-      chSync <- atomically newTChan
       let req1 = IdeRequest "cmd1" (Map.fromList [])
           cr1 = CReq "test" 1 req1 chan
       let req2 = IdeRequest "cmd2" (Map.fromList [])
diff --git a/test/ExtensibleStateSpec.hs b/test/ExtensibleStateSpec.hs
index ac2aa1f2c..3b54f3d7e 100644
--- a/test/ExtensibleStateSpec.hs
+++ b/test/ExtensibleStateSpec.hs
@@ -1,14 +1,11 @@
 {-# LANGUAGE OverloadedStrings #-}
 module ExtensibleStateSpec where
 
-import           Control.Concurrent
 import           Control.Concurrent.STM.TChan
-import           Control.Monad.IO.Class
 import           Control.Monad.STM
 import           Data.Aeson
 import qualified Data.HashMap.Strict as H
 import qualified Data.Text as T
-import qualified Data.HashMap.Strict as HM
 import qualified Data.Map as Map
 import           Data.Typeable
 import           Haskell.Ide.Engine.Dispatcher
@@ -17,8 +14,6 @@ import           Haskell.Ide.Engine.Monad
 import           Haskell.Ide.Engine.MonadFunctions
 import           Haskell.Ide.Engine.PluginDescriptor
 import           Haskell.Ide.Engine.Types
-import           Haskell.Ide.Engine.Utils
-import           Haskell.Ide.Engine.PluginDescriptor
 
 import           Test.Hspec
 
@@ -55,7 +50,7 @@ testPlugins :: TChan () -> Plugins
 testPlugins chSync = Map.fromList [("test",testDescriptor chSync)]
 
 testDescriptor :: TChan () -> UntaggedPluginDescriptor
-testDescriptor chSync = PluginDescriptor
+testDescriptor _chSync = PluginDescriptor
   {
     pdUIShortName = "testDescriptor"
   , pdUIOverview = "PluginDescriptor for testing Dispatcher"
diff --git a/test/HaRePluginSpec.hs b/test/HaRePluginSpec.hs
index 6c71db268..41467ea1c 100644
--- a/test/HaRePluginSpec.hs
+++ b/test/HaRePluginSpec.hs
@@ -4,7 +4,6 @@ module HaRePluginSpec where
 import           Control.Concurrent.STM.TChan
 import           Control.Monad.STM
 import           Data.Aeson
-import           Data.Algorithm.Diff
 import qualified Data.Map as Map
 import           Haskell.Ide.Engine.Dispatcher
 import           Haskell.Ide.Engine.Monad
diff --git a/test/IdeBackendPluginSpec.hs b/test/IdeBackendPluginSpec.hs
index 8b58a73d4..db903bdb3 100644
--- a/test/IdeBackendPluginSpec.hs
+++ b/test/IdeBackendPluginSpec.hs
@@ -2,7 +2,6 @@
 module IdeBackendPluginSpec where
 
 import           Control.Concurrent.STM.TChan
-import           Control.Exception
 import           Control.Monad.STM
 import           Data.Aeson
 import qualified Data.HashMap.Strict as H