diff --git a/behat/symfony2-extension/2.1/features/bootstrap/FeatureContext.php b/behat/symfony2-extension/2.1/features/bootstrap/FeatureContext.php
index 23e3386a..bfb1459a 100644
--- a/behat/symfony2-extension/2.1/features/bootstrap/FeatureContext.php
+++ b/behat/symfony2-extension/2.1/features/bootstrap/FeatureContext.php
@@ -41,6 +41,8 @@ class FeatureContext implements Context
      */
     public function theResponseShouldBeReceived()
     {
-        assert($this->response !== null);
+        if ($this->response === null) {
+            throw new \RuntimeException('No response received');
+        }
     }
 }