diff --git a/src/Symfony/Bridge/PhpUnit/ClockMock.php b/src/Symfony/Bridge/PhpUnit/ClockMock.php
index 4b745e38e8..b81fee9658 100644
--- a/src/Symfony/Bridge/PhpUnit/ClockMock.php
+++ b/src/Symfony/Bridge/PhpUnit/ClockMock.php
@@ -66,7 +66,7 @@ class ClockMock
             return self::$now;
         }
 
-        return sprintf("%0.6f %d\n", $now - (int) $now, (int) self::$now);
+        return sprintf("%0.6f %d\n", self::$now - (int) self::$now, (int) self::$now);
     }
 
     public static function register($class)