diff --git a/wagtail/wagtailadmin/static/wagtailadmin/scss/core.scss b/wagtail/wagtailadmin/static/wagtailadmin/scss/core.scss
index 55e27b067..bd51a7595 100644
--- a/wagtail/wagtailadmin/static/wagtailadmin/scss/core.scss
+++ b/wagtail/wagtailadmin/static/wagtailadmin/scss/core.scss
@@ -193,6 +193,7 @@ img{
 
             .menu-snippets &.menu-snippets,
             .menu-users &.menu-users,
+            .menu-groups &.menu-groups,
             .menu-snippets &.menu-snippets,
             .menu-documents &.menu-documents,
             .menu-images &.menu-images,
@@ -792,4 +793,4 @@ footer,
 }
 .nav-main a, a{
     @include transition(color 0.2s ease, background-color 0.2s ease);
-}
\ No newline at end of file
+}