--- a/toolkit/themes/osx/global/autocomplete.css
+++ b/toolkit/themes/osx/global/autocomplete.css
@@ -41,16 +41,21 @@ panel[type="autocomplete-richlistbox"],
 .autocomplete-history-popup {
   padding: 0px !important;
   color: -moz-FieldText;
   background-color: -moz-Field;
   font: icon;
   -moz-appearance: none;
 }
 
+/* OSX gives the awesomebar an extra 1px at the top - https://bugzilla.mozilla.org/show_bug.cgi?id=1393406 */
+#PopupAutoCompleteRichResult {
+  margin-top: 1px;
+}
+
 .autocomplete-history-popup {
   max-height: 180px;
 }
 
 /* ::::: tree ::::: */
 
 .autocomplete-tree {
   -moz-appearance: none !important;