diff --git a/wp-includes/media.php b/wp-includes/media.php
index 364817712f..7ecae01cd1 100644
--- a/wp-includes/media.php
+++ b/wp-includes/media.php
@@ -1008,7 +1008,7 @@ function gallery_shortcode( $attr ) {
 
 	$selector = "gallery-{$instance}";
 
-	$gallery_style = $gallery_div = '';
+	$gallery_style = '';
 
 	/**
 	 * Filter whether to print default gallery styles.