diff --git a/src/Stack/Build/Cache.hs b/src/Stack/Build/Cache.hs
index 5fe6413517..55e80194ad 100644
--- a/src/Stack/Build/Cache.hs
+++ b/src/Stack/Build/Cache.hs
@@ -2,6 +2,7 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE TemplateHaskell       #-}
 {-# LANGUAGE TupleSections         #-}
+{-# LANGUAGE ConstraintKinds       #-}
 -- | Cache information about previous builds
 module Stack.Build.Cache
     ( tryGetBuildCache