diff --git a/src/Data/GADT/Internal.hs b/src/Data/GADT/Internal.hs
index 1fe29a4..d219599 100644
--- a/src/Data/GADT/Internal.hs
+++ b/src/Data/GADT/Internal.hs
@@ -14,7 +14,7 @@
 #else
 {-# LANGUAGE Trustworthy         #-}
 #endif
-#undef GH
+#undef GHC
 #endif
 module Data.GADT.Internal where