diff --git a/src/Linear/Trace.hs b/src/Linear/Trace.hs
index 2c7a5c4..005152b 100644
--- a/src/Linear/Trace.hs
+++ b/src/Linear/Trace.hs
@@ -1,6 +1,9 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE TypeOperators #-}
 {-# LANGUAGE DefaultSignatures #-}
+#if __GLASGOW_HASKELL__ >= 707
+{-# LANGUAGE PolyKinds #-}
+#endif
 #if __GLASGOW_HASKELL__ >= 702 && __GLASGOW_HASKELL__ < 710
 {-# LANGUAGE Trustworthy #-}
 #endif