diff --git a/src/Extension/Loader/Facade/Caller.php b/src/Extension/Loader/Facade/Caller.php
index e01c21b..604c4c3 100644
--- a/src/Extension/Loader/Facade/Caller.php
+++ b/src/Extension/Loader/Facade/Caller.php
@@ -86,7 +86,7 @@ public function __call($method, array $arguments)
         }
 
         $result  = forward_static_call_array([$this->facade, $method], $arguments);
-        $is_safe = ($is_safe && (is_string($result) || (is_callable($result) && method_exists($result, '__toString'))));
+        $is_safe = ($is_safe && (is_string($result) || (is_object($result) && method_exists($result, '__toString'))));
 
         return ($is_safe) ? new Markup($result, $this->options['charset']) : $result;
     }