diff --git a/resources/css/ext.uls-vector.less b/resources/css/ext.uls-vector.less
index 6dca27d3..da149ecf 100644
--- a/resources/css/ext.uls-vector.less
+++ b/resources/css/ext.uls-vector.less
@@ -5,7 +5,7 @@
 .skin-vector {
 	.uls-menu {
 		border-color: #c8ccd1;
-		.box-shadow( 0 2px 2px 0 rgba( 0, 0, 0, 0.25 ) );
+		box-shadow: 0 2px 2px 0 rgba( 0, 0, 0, 0.25 );
 		// Not inherited from `.mw-body-content`, as we insert at `body`.
 		font-size: 0.875em;
 	}