diff --git a/ghc/compiler/parser/Ctype.lhs b/ghc/compiler/parser/Ctype.lhs
index adcaec27efbbfa27931a89ef59ae3f6381c3a27e..4d9c6007d72724098478229661da4cbaf27ddb70 100644
--- a/ghc/compiler/parser/Ctype.lhs
+++ b/ghc/compiler/parser/Ctype.lhs
@@ -35,6 +35,7 @@ The predicates below look costly, but aren't, GHC+GCC do a great job
 at the big case below.
 
 \begin{code}
+{-# INLINE is_ctype #-}
 is_ctype :: Int -> Char# -> Bool
 is_ctype mask c = (fromIntegral (charType (C# c)) .&. fromIntegral mask) /= (0::Int32)