diff --git a/src/SM/Callback/Callback.php b/src/SM/Callback/Callback.php
index 8ffdb19..a2783a6 100644
--- a/src/SM/Callback/Callback.php
+++ b/src/SM/Callback/Callback.php
@@ -58,7 +58,10 @@ public function call(TransitionEvent $event)
             $expr = new ExpressionLanguage();
             $args = array_map(
                 function($arg) use($expr, $event) {
-                    if (!is_string($arg)) {
+                    if (
+                        !is_string($arg) ||
+                        !($this->str_starts_with($arg, 'object') || $this->str_starts_with($arg, 'event'))
+                    ) {
                         return $arg;
                     }
 
@@ -141,4 +144,13 @@ protected function filterCallable($callable, TransitionEvent $event): callable
 
         return $callable;
     }
+
+    protected function str_starts_with(string $haystack, string $needle): bool
+    {
+        if (!function_exists('str_starts_with')) {
+            return $needle !== '' && strncmp($haystack, $needle, strlen($needle)) === 0;
+        }
+
+        return \str_starts_with($haystack, $needle);
+    }
 }