diff --git a/src/wp-includes/functions.php b/src/wp-includes/functions.php
index 8ca7da28af..8cd4af4f68 100644
--- a/src/wp-includes/functions.php
+++ b/src/wp-includes/functions.php
@@ -1326,7 +1326,7 @@ function wp_get_referer() {
  * @return string|bool False if no original referer or original referer if set.
  */
 function wp_get_original_referer() {
-	if ( !empty( $_REQUEST['_wp_original_http_referer'] ) )
+	if ( ! empty( $_REQUEST['_wp_original_http_referer'] ) && function_exists( 'wp_validate_redirect' ) )
 		return wp_validate_redirect( wp_unslash( $_REQUEST['_wp_original_http_referer'] ), false );
 	return false;
 }