diff --git a/themes/base/jquery.ui.dialog.css b/themes/base/jquery.ui.dialog.css
index c5499d8dbb5..b49a4a76da1 100644
--- a/themes/base/jquery.ui.dialog.css
+++ b/themes/base/jquery.ui.dialog.css
@@ -31,7 +31,7 @@
 	position: absolute;
 	right: .3em;
 	top: 50%;
-	width: 21px;
+	width: 20px;
 	margin: -10px 0 0 0;
 	padding: 1px;
 	height: 20px;