diff --git a/Yesod/Form.hs b/Yesod/Form.hs
index e7c411c6..f2462148 100644
--- a/Yesod/Form.hs
+++ b/Yesod/Form.hs
@@ -24,6 +24,8 @@ module Yesod.Form
       -- * Field/form helpers
     , fieldsToTable
     , fieldsToPlain
+    , checkForm
+      -- * Fields
     , module Yesod.Form.Fields
       -- * Template Haskell
     , mkToForm
diff --git a/Yesod/Form/Core.hs b/Yesod/Form/Core.hs
index 75f4c9e2..e5ddea00 100644
--- a/Yesod/Form/Core.hs
+++ b/Yesod/Form/Core.hs
@@ -13,6 +13,7 @@ module Yesod.Form.Core
     , optionalFieldHelper
     , fieldsToInput
     , mapFormXml
+    , checkForm
       -- * Data types
     , FieldInfo (..)
     , FormFieldSettings (..)
@@ -230,3 +231,12 @@ type Formlet sub y a = Maybe a -> Form sub y a
 type FormField sub y = GForm sub y [FieldInfo sub y]
 type FormletField sub y a = Maybe a -> FormField sub y a
 type FormInput sub y = GForm sub y [GWidget sub y ()]
+
+checkForm :: (a -> FormResult b) -> GForm s m x a -> GForm s m x b
+checkForm f (GForm form) = GForm $ \env fenv -> do
+    (res, xml, enc) <- form env fenv
+    let res' = case res of
+                    FormSuccess a -> f a
+                    FormFailure e -> FormFailure e
+                    FormMissing -> FormMissing
+    return (res', xml, enc)
diff --git a/Yesod/Yesod.hs b/Yesod/Yesod.hs
index 06475539..b4c9fb1a 100644
--- a/Yesod/Yesod.hs
+++ b/Yesod/Yesod.hs
@@ -53,7 +53,6 @@ import Web.Routes.Site (Site)
 import Control.Monad.Trans.Class (MonadTrans (..))
 import Control.Monad.Attempt (Failure)
 import qualified Data.ByteString as S
-import qualified Data.ByteString.Char8 as S8
 import qualified Network.Wai.Middleware.CleanPath
 import Web.Routes (encodePathInfo)
 import qualified Data.ByteString.Lazy as L
@@ -268,10 +267,10 @@ applyLayout' s = fmap chooseRep . applyLayout s mempty
 defaultErrorHandler :: Yesod y => ErrorResponse -> GHandler sub y ChooseRep
 defaultErrorHandler NotFound = do
     r <- waiRequest
-    let pi = BSU.toString $ pathInfo r
+    let path = BSU.toString $ pathInfo r
     applyLayout' "Not Found" $ [$hamlet|
 %h1 Not Found
-%p $pi$
+%p $path$
 |]
   where
     pathInfo = W.pathInfo