diff --git a/src/Stack/Coverage.hs b/src/Stack/Coverage.hs
index d95fa332..f80e121a 100644
--- a/src/Stack/Coverage.hs
+++ b/src/Stack/Coverage.hs
@@ -235,7 +235,7 @@ generateHpcReportForTargets opts tixFiles targetNames = do
                              case nc of
                                  CTest testName ->
                                      liftM (pkgPath </>) $ parseRelFile (T.unpack testName ++ "/" ++ T.unpack testName ++ ".tix")
-                                 _ -> fail $
+                                 _ -> liftIO $ fail $
                                      "Can't specify anything except test-suites as hpc report targets (" ++
                                      packageNameString name ++
                                      " is used with a non test-suite target)"
diff --git a/src/Stack/Package.hs b/src/Stack/Package.hs
index b69337ce..08eb9b9f 100644
--- a/src/Stack/Package.hs
+++ b/src/Stack/Package.hs
@@ -463,7 +463,7 @@ makeObjectFilePathFromC
 makeObjectFilePathFromC cabalDir namedComponent distDir cFilePath = do
     relCFilePath <- stripProperPrefix cabalDir cFilePath
     relOFilePath <-
-        parseRelFile (replaceExtension (toFilePath relCFilePath) "o")
+        parseRelFile (System.FilePath.replaceExtension (toFilePath relCFilePath) "o")
     return (componentOutputDir namedComponent distDir </> relOFilePath)
 
 -- | Make the global autogen dir if Cabal version is new enough.
diff --git a/src/Stack/Script.hs b/src/Stack/Script.hs
index c63c9f62..70257be1 100644
--- a/src/Stack/Script.hs
+++ b/src/Stack/Script.hs
@@ -172,8 +172,8 @@ scriptCmd opts = do
 
   toExeName fp =
     if osIsWindows
-      then replaceExtension fp "exe"
-      else dropExtension fp
+      then System.FilePath.replaceExtension fp "exe"
+      else System.FilePath.dropExtension fp
 
 getPackagesFromImports
   :: FilePath -- ^ script filename
diff --git a/src/Stack/Setup.hs b/src/Stack/Setup.hs
index 8bbfc45c..5c5b028c 100644
--- a/src/Stack/Setup.hs
+++ b/src/Stack/Setup.hs
@@ -876,7 +876,7 @@ buildGhcFromSource getSetupInfo' installed (CompilerRepository url) commitId fla
          (_,files) <- listDir (cwd </> bindistPath)
          let
            isBindist p = "ghc-" `isPrefixOf` (toFilePath (filename p))
-                         && fileExtension (filename p) == ".xz"
+                         && (maybe "" id (fileExtension (filename p))) == ".xz"
            mbindist = filter isBindist files
          case mbindist of
            [bindist] -> do
diff --git a/src/Stack/Storage/Project.hs b/src/Stack/Storage/Project.hs
index dc5318d8..984e6259 100644
--- a/src/Stack/Storage/Project.hs
+++ b/src/Stack/Storage/Project.hs
@@ -12,6 +12,9 @@
 {-# LANGUAGE UndecidableInstances #-}
 {-# OPTIONS_GHC -Wno-unused-top-binds -Wno-identities #-}
 
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE StandaloneDeriving #-}
+
 -- | Work with SQLite database used for caches across a single project.
 module Stack.Storage.Project
     ( initProjectStorage
diff --git a/src/Stack/Storage/User.hs b/src/Stack/Storage/User.hs
index 3845b094..09695344 100644
--- a/src/Stack/Storage/User.hs
+++ b/src/Stack/Storage/User.hs
@@ -12,6 +12,9 @@
 {-# LANGUAGE UndecidableInstances #-}
 {-# OPTIONS_GHC -Wno-unused-top-binds -Wno-identities #-}
 
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE StandaloneDeriving #-}
+
 -- | Work with SQLite database used for caches across an entire user account.
 module Stack.Storage.User
     ( initUserStorage
diff --git a/src/Stack/Types/Config.hs b/src/Stack/Types/Config.hs
index a5cc22b5..a329d353 100644
--- a/src/Stack/Types/Config.hs
+++ b/src/Stack/Types/Config.hs
@@ -406,7 +406,7 @@ instance FromJSON CabalConfigKey where
 instance FromJSONKey CabalConfigKey where
   fromJSONKey = FromJSONKeyTextParser parseCabalConfigKey
 
-parseCabalConfigKey :: Monad m => Text -> m CabalConfigKey
+parseCabalConfigKey :: MonadFail m => Text -> m CabalConfigKey
 parseCabalConfigKey "$targets" = pure CCKTargets
 parseCabalConfigKey "$locals" = pure CCKLocals
 parseCabalConfigKey "$everything" = pure CCKEverything
@@ -974,7 +974,7 @@ parseConfigMonoidObject rootDir obj = do
 
     return ConfigMonoid {..}
   where
-    handleExplicitSetupDep :: Monad m => (Text, Bool) -> m (Maybe PackageName, Bool)
+    handleExplicitSetupDep :: MonadFail m => (Text, Bool) -> m (Maybe PackageName, Bool)
     handleExplicitSetupDep (name', b) = do
         name <-
             if name' == "*"