diff --git a/sourcefiles/modern/plugins/jquery/jquery-ui-1.12.1.js b/sourcefiles/modern/plugins/jquery/jquery-ui-1.12.1.js
index 02f5c16e7..cf43cb6cb 100644
--- a/sourcefiles/modern/plugins/jquery/jquery-ui-1.12.1.js
+++ b/sourcefiles/modern/plugins/jquery/jquery-ui-1.12.1.js
@@ -1561,7 +1561,7 @@ var keycode = $.ui.keyCode = {
 
 // Internal use only
 var escapeSelector = $.ui.escapeSelector = ( function() {
-	var selectorEscape = /([!"#$%&'()*+,./:;<=>?@[\]^`{|}~])/g;
+	var selectorEscape = /([!"#$%&'()*+,./:;<=>?@[\\\]^`{|}~])/g;
 	return function( selector ) {
 		return selector.replace( selectorEscape, "\\$1" );
 	};