diff --git a/wp-admin/includes/meta-boxes.php b/wp-admin/includes/meta-boxes.php
index c0ac23b452..bd81cb1e32 100644
--- a/wp-admin/includes/meta-boxes.php
+++ b/wp-admin/includes/meta-boxes.php
@@ -1036,7 +1036,8 @@ function post_thumbnail_meta_box( $post ) {
 			frame.toolbar.on( 'activate:select', function() {
 				frame.toolbar.view().add({
 					select: {
-						text: update,
+						style: 'primary',
+						text:  update,
 
 						click: function() {
 							var selection = frame.state().get('selection'),