diff --git a/layout/style/forms.css b/layout/style/forms.css
index b05573a89725..d7745abe2c3f 100644
--- a/layout/style/forms.css
+++ b/layout/style/forms.css
@@ -349,7 +349,7 @@ optgroup[disabled] {
 /* hidden inputs */
 input[type="hidden"] {
   -moz-appearance: none;
-  display: none;
+  display: none !important;
   padding: 0;
   border: 0;
   cursor: auto;