diff --git a/Yesod/Handler.hs b/Yesod/Handler.hs
index 1dcfa55d..b28c374c 100644
--- a/Yesod/Handler.hs
+++ b/Yesod/Handler.hs
@@ -28,6 +28,7 @@ module Yesod.Handler
     , redirect
     , notFound
     , permissionDenied
+    , invalidArgs
       -- * Setting headers
     , addCookie
     , deleteCookie
@@ -81,8 +82,8 @@ instance Exception e => Failure e (Handler yesod) where
     failure e = Handler $ \_ -> return ([], HCError e)
 instance MonadRequestReader (Handler yesod) where
     askRawRequest = Handler $ \(rr, _) -> return ([], HCContent rr)
-    invalidParam _pt _pn _pe = error "invalidParam"
-    authRequired = error "authRequired"
+    invalidParam _pt pn pe = invalidArgs [(pn, pe)]
+    authRequired = permissionDenied
 
 getYesod :: Handler yesod yesod
 getYesod = Handler $ \(_, yesod) -> return ([], HCContent yesod)
@@ -210,6 +211,9 @@ notFound = errorResult NotFound
 permissionDenied :: Handler yesod a
 permissionDenied = errorResult PermissionDenied
 
+invalidArgs :: [(ParamName, ParamValue)] -> Handler yesod a
+invalidArgs = errorResult . InvalidArgs
+
 ------- Headers
 -- | Set the cookie on the client.
 addCookie :: Int -- ^ minutes to timeout
diff --git a/test/errors.hs b/test/errors.hs
new file mode 100644
index 00000000..b841f1ba
--- /dev/null
+++ b/test/errors.hs
@@ -0,0 +1,43 @@
+{-# LANGUAGE QuasiQuotes #-}
+import Yesod
+import Hack
+import Data.Default
+import Data.List
+
+data Errors = Errors
+instance Yesod Errors where
+    handlers = [$resources|
+/denied:
+    Get: denied
+/needs-ident:
+    Get: needsIdent
+/has-args:
+    Get: hasArgs
+|]
+
+denied :: Handler Errors ()
+denied = permissionDenied
+
+needsIdent :: Handler Errors HtmlObject
+needsIdent = do
+    i <- identifier
+    return $ toHtmlObject i
+
+hasArgs :: Handler Errors HtmlObject
+hasArgs = do
+    -- FIXME this test needs more work
+    a <- getParam "firstParam"
+    b <- getParam "secondParam"
+    return $ toHtmlObject [a :: String, b]
+
+main = do
+    let app = toHackApp Errors
+    res <- app $ def { pathInfo = "/denied/" }
+    print res
+    print $ "Permission denied" `isInfixOf` show res
+    res' <- app $ def { pathInfo = "/needs-ident/" }
+    print res'
+    print $ "Permission denied" `isInfixOf` show res'
+    res3 <- app $ def { pathInfo = "/has-args/" }
+    print res3
+    print $ "secondParam" `isInfixOf` show res3