diff --git a/src/Handler/Utils/Form.hs b/src/Handler/Utils/Form.hs
index 8cc02782a..22e1cc88b 100644
--- a/src/Handler/Utils/Form.hs
+++ b/src/Handler/Utils/Form.hs
@@ -64,9 +64,12 @@ buttonForm html = do
     accResult = Foldable.foldr accResult' FormMissing
 
     accResult' :: FormResult (Maybe a) -> FormResult a -> FormResult a
-    accResult' (FormSuccess _) (FormSuccess _) = FormFailure ["Ambiguous parse"]
+    accResult' (FormSuccess (Just _)) (FormSuccess _) = FormFailure ["Ambiguous parse"]
     accResult' (FormSuccess (Just x)) _ = FormSuccess x
-    accResult' _ x = x
+    accResult' _ x@(FormSuccess _) = x
+    accResult' (FormSuccess Nothing) x = x
+    accResult' FormMissing _ = FormMissing
+    accResult' (FormFailure errs) _ = FormFailure errs
   
 ----------------------------
 -- Buttons (old version ) --