diff --git a/Yesod/Helpers/Static.hs b/Yesod/Helpers/Static.hs
index 744de2ad..6c3c4e53 100644
--- a/Yesod/Helpers/Static.hs
+++ b/Yesod/Helpers/Static.hs
@@ -153,9 +153,11 @@ staticFiles fp = do
     fs <- qRunIO $ getFileList fp
     concat `fmap` mapM go fs
   where
-    replace' '.' = '_'
-    replace' '-' = '_'
-    replace' c = c
+    replace' c
+        | 'A' <= c && c <= 'Z' = c
+        | 'a' <= c && c <= 'z' = c
+        | '0' <= c && c <= '9' = c
+        | otherwise = '_'
     go f = do
         let name = mkName $ intercalate "_" $ map (map replace') f
         f' <- lift f
diff --git a/yesod.cabal b/yesod.cabal
index a5c1278f..efdfe931 100644
--- a/yesod.cabal
+++ b/yesod.cabal
@@ -1,5 +1,5 @@
 name:            yesod
-version:         0.6.3
+version:         0.6.3.1
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>