diff --git a/ui/jquery.ui.selectmenu.js b/ui/jquery.ui.selectmenu.js
index 4ec8fcd8df..99c314f484 100644
--- a/ui/jquery.ui.selectmenu.js
+++ b/ui/jquery.ui.selectmenu.js
@@ -114,7 +114,7 @@ $.widget( "ui.selectmenu", {
 		// Wrap menu
 		this.menuWrap = $( "<div>", {
 				"class": "ui-selectmenu-menu",
-				width: this.button.outerWidth()
+				outerWidth: this.button.outerWidth()
 			})
 			.append( this.menu )
 			.appendTo( this._appendTo() );