diff --git a/packages/mdc-tab/mdc-tab.scss b/packages/mdc-tab/mdc-tab.scss
index c670a16a83c..079f7f93852 100644
--- a/packages/mdc-tab/mdc-tab.scss
+++ b/packages/mdc-tab/mdc-tab.scss
@@ -52,7 +52,7 @@
   z-index: 1;
 
   // Firefox still draws a dotted border around focused buttons unless specifically overridden.
-  ::-moz-focus-inner {
+  &::-moz-focus-inner {
     padding: 0;
     border: 0;
   }