diff --git a/lib/Cake/Routing/Route/CakeRoute.php b/lib/Cake/Routing/Route/CakeRoute.php
index 85dbb59c9..8149ce39a 100644
--- a/lib/Cake/Routing/Route/CakeRoute.php
+++ b/lib/Cake/Routing/Route/CakeRoute.php
@@ -470,7 +470,8 @@ class CakeRoute {
 		//check patterns for routed params
 		if (!empty($this->options)) {
 			foreach ($this->options as $key => $pattern) {
-				if (array_key_exists($key, $url) && !preg_match('#^' . $pattern . '$#', $url[$key])) {
+				//Fixing deprecation notice about null $subject in PHP8.1.
+				if (array_key_exists($key, $url) && !preg_match('#^' . $pattern . '$#', $url[$key] ?? "")) {
 					return false;
 				}
 			}