diff --git a/src/RunGhc.hs b/src/RunGhc.hs
index 2beea412bc1ba18635f320d0099bf6f2f6f80add..a7dd5a96bc9153d0aa300fa8cecf92d29ed4fda3 100644
--- a/src/RunGhc.hs
+++ b/src/RunGhc.hs
@@ -110,7 +110,7 @@ toHsWord w x = "W# " <> parens (extendFn <> " " <> parens x)
   where
 #if __GLASGOW_HASKELL__ >= 904
     extendFn = "word" ++ show n ++ "ToWord#"
-    n = widthInBits w
+    n = widthBits w
 #elif defined(WORD_SIZE_32BIT)
     extendFn
       | w == W32  = "word32ToWord#"