diff --git a/yesod-core/Yesod/Handler.hs b/yesod-core/Yesod/Handler.hs
index 2d3ceac3..554263dd 100644
--- a/yesod-core/Yesod/Handler.hs
+++ b/yesod-core/Yesod/Handler.hs
@@ -463,8 +463,8 @@ runHandler handler mrender sroute tomr master sub upload log' =
   YesodApp $ \eh rr cts initSession -> do
     let toErrorHandler e =
             case fromException e of
-                Just x -> x
-                Nothing -> InternalError $ T.pack $ show e
+                Just (HCError x) -> x
+                _ -> InternalError $ T.pack $ show e
     istate <- liftIO $ I.newIORef GHState
         { ghsSession = initSession
         , ghsRBC = Nothing
diff --git a/yesod-core/Yesod/Internal.hs b/yesod-core/Yesod/Internal.hs
index d1560e30..23ebc15f 100644
--- a/yesod-core/Yesod/Internal.hs
+++ b/yesod-core/Yesod/Internal.hs
@@ -59,7 +59,6 @@ data ErrorResponse =
     | PermissionDenied Text
     | BadMethod H.Method
     deriving (Show, Eq, Typeable)
-instance Exception ErrorResponse
 
 ----- header stuff
 -- | Headers to be added to a 'Result'.