diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index 0727086aee..6287edef40 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -3771,7 +3771,7 @@ function _wp_customize_loader_settings() {
 function wp_customize_url( $stylesheet = '' ) {
 	$url = admin_url( 'customize.php' );
 	if ( $stylesheet ) {
-		$url .= '?theme=' . urlencode( $stylesheet );
+		$url = add_query_arg( 'theme', urlencode( $stylesheet ), $url );
 	}
 	return esc_url( $url );
 }
diff --git a/wp-includes/version.php b/wp-includes/version.php
index da8b26e215..0c5a8cb082 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.9-alpha-60498';
+$wp_version = '6.9-alpha-60499';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.