diff --git a/toolkit/themes/winstripe/global/autocomplete.css b/toolkit/themes/winstripe/global/autocomplete.css
index 851bc0ab89bb..db7738cdbad5 100644
--- a/toolkit/themes/winstripe/global/autocomplete.css
+++ b/toolkit/themes/winstripe/global/autocomplete.css
@@ -169,6 +169,7 @@ textbox[chromedir="rtl"] .autocomplete-history-dropmarker {
 
 panel[type="autocomplete"],
 .autocomplete-history-popup {
+  -moz-appearance: none;
   border-width: 1px;
   -moz-border-top-colors: ThreeDDarkShadow;
   -moz-border-right-colors: ThreeDDarkShadow;
diff --git a/toolkit/themes/winstripe/global/popup.css b/toolkit/themes/winstripe/global/popup.css
index cd4b43aecdbe..149a47b2beba 100644
--- a/toolkit/themes/winstripe/global/popup.css
+++ b/toolkit/themes/winstripe/global/popup.css
@@ -93,6 +93,7 @@ tooltip[titletip="true"] {
 
 menulist > menupopup,
 .menulist-menupopup {
+  -moz-appearance: none;
   border-width: 1px;
   -moz-border-top-colors: -moz-FieldText;
   -moz-border-right-colors: -moz-FieldText;