diff --git a/src/wp-admin/css/common.css b/src/wp-admin/css/common.css
index 5f03d8a381..74f78bc4e3 100644
--- a/src/wp-admin/css/common.css
+++ b/src/wp-admin/css/common.css
@@ -2054,6 +2054,7 @@ h2 .nav-tab {
 
 .metabox-holder h3.hndle, /* Back-compat for pre-4.4 */
 .metabox-holder .stuffbox > h3, /* Back-compat for pre-4.4 */
+.metabox-holder .postbox > h3, /* Back-compat for pre-4.4 */
 .metabox-holder h2 {
 	font-size: 14px;
 	padding: 8px 12px;
@@ -3436,6 +3437,7 @@ img {
 
 	.metabox-holder h3.hndle, /* Back-compat for pre-4.4 */
 	.metabox-holder .stuffbox > h3, /* Back-compat for pre-4.4 */
+	.metabox-holder .postbox > h3, /* Back-compat for pre-4.4 */
 	.metabox-holder h2 {
 		padding: 12px;
 	}