diff --git a/lib/WebDriver/WebDriver.php b/lib/WebDriver/WebDriver.php
index b97eb87..0e204f4 100644
--- a/lib/WebDriver/WebDriver.php
+++ b/lib/WebDriver/WebDriver.php
@@ -166,7 +166,7 @@ public function sessions()
      */
     private function filter($capabilities)
     {
-        return $capabilities ? array_values(array_filter($capabilities, function ($capability) { return self::$w3cCapabilities[$capability] ?? 0; })) : null;
+        return $capabilities ? array_filter($capabilities, function ($key) { return isset(self::$w3cCapabilities[$key]) || str_contains($key, ':'); }, ARRAY_FILTER_USE_KEY) : null;
     }
 
     /**