diff --git a/src/Symfony/Component/BrowserKit/Cookie.php b/src/Symfony/Component/BrowserKit/Cookie.php
index 1e2c64ce63f5..bce5613cf7a6 100644
--- a/src/Symfony/Component/BrowserKit/Cookie.php
+++ b/src/Symfony/Component/BrowserKit/Cookie.php
@@ -127,7 +127,7 @@ public static function fromString($cookie, $url = null)
         $parts = explode(';', $cookie);
 
         if (false === strpos($parts[0], '=')) {
-            throw new \InvalidArgumentException('The cookie string "%s" is not valid.');
+            throw new \InvalidArgumentException(sprintf('The cookie string "%s" is not valid.', $parts[0]));
         }
 
         list($name, $value) = explode('=', array_shift($parts), 2);