diff --git a/src/Path/Extended.hs b/src/Path/Extended.hs
index e6e82ac718..02f5950a7b 100644
--- a/src/Path/Extended.hs
+++ b/src/Path/Extended.hs
@@ -2,15 +2,40 @@
 
 module Path.Extended 
  ( fileExtension
+ , addExtension
+ , replaceExtension
  ) where
 
 import           Control.Monad.Catch
-import qualified Path as Path
+import qualified Path
+import           Path (Path, File)
 
-fileExtension :: MonadThrow m => Path.Path b Path.File -> m String
+fileExtension :: MonadThrow m => Path b File -> m String
 fileExtension = 
 #if MIN_VERSION_path(0,7,0)
     Path.fileExtension
 #else
     pure . Path.fileExtension
 #endif
+
+addExtension :: MonadThrow m
+  => String
+  -> Path b File
+  -> m (Path b File)
+addExtension =
+#if MIN_VERSION_path(0,7,0)
+    Path.addExtension
+#else
+    Path.addFileExtension
+#endif
+
+replaceExtension :: MonadThrow m
+  => String
+  -> Path b File
+  -> m (Path b File)
+replaceExtension =
+#if MIN_VERSION_path(0,7,0)
+    Path.replaceExtension
+#else
+    flip (Path.-<.>)
+#endif
diff --git a/src/Stack/Coverage.hs b/src/Stack/Coverage.hs
index 0de1ec8613..ede8bc20cc 100644
--- a/src/Stack/Coverage.hs
+++ b/src/Stack/Coverage.hs
@@ -46,7 +46,7 @@ import           RIO.Process
 import           Trace.Hpc.Tix
 import           Web.Browser (openBrowser)
 
-data CoverageException = NonTestSuiteTarget PackageName deriving Typeable
+newtype CoverageException = NonTestSuiteTarget PackageName deriving Typeable
 
 instance Exception CoverageException
 instance Show CoverageException where
diff --git a/src/Stack/Docker.hs b/src/Stack/Docker.hs
index bced11d6c9..0f721fbe83 100644
--- a/src/Stack/Docker.hs
+++ b/src/Stack/Docker.hs
@@ -41,7 +41,12 @@ import qualified Data.Text.Encoding as T
 import           Data.Time (UTCTime)
 import           Data.Version (showVersion)
 import           Distribution.Version (mkVersion)
+#if MIN_VERSION_path(0,7,0)
+import           Path hiding (replaceExtension)
+#else
 import           Path
+#endif
+import           Path.Extended (replaceExtension)
 import           Path.Extra (toFilePathNoTrailingSep)
 import           Path.IO hiding (canonicalizePath)
 import qualified Paths_stack as Meta
@@ -150,7 +155,7 @@ getCmdArgs docker imageInfo isRemoteDocker = do
         exePath <- ensureDockerStackExe dockerContainerPlatform
         cmdArgs args exePath
     cmdArgs args exePath = do
-        exeBase <- exePath -<.> ""
+        exeBase <- replaceExtension "" exePath
         let mountPath = hostBinDir FP.</> toFilePath (filename exeBase)
         return (mountPath, args, [], [Mount (toFilePath exePath) mountPath])
 
diff --git a/src/Stack/Lock.hs b/src/Stack/Lock.hs
index fa1ff73a23..642fb804f8 100644
--- a/src/Stack/Lock.hs
+++ b/src/Stack/Lock.hs
@@ -16,7 +16,8 @@ import qualified Data.List.NonEmpty as NE
 import qualified Data.Map as Map
 import qualified Data.Yaml as Yaml
 import Pantry
-import Path (addFileExtension, parent)
+import Path (parent)
+import Path.Extended (addExtension)
 import Path.IO (doesFileExist)
 import Stack.Prelude
 import Stack.SourceMap
@@ -94,7 +95,7 @@ lockCachedWanted ::
         -> RIO env ( SMWanted, [CompletedPLI]))
     -> RIO env SMWanted
 lockCachedWanted stackFile resolver fillWanted = do
-    lockFile <- liftIO $ addFileExtension "lock" stackFile
+    lockFile <- liftIO $ addExtension ".lock" stackFile
     let getLockExists = doesFileExist lockFile
     lfb <- view lockFileBehaviorL
     readLockFile <-