diff --git a/Resources/config/config.xml b/Resources/config/config.xml
index dcec2e8..06f0cda 100644
--- a/Resources/config/config.xml
+++ b/Resources/config/config.xml
@@ -18,7 +18,7 @@
             <argument /> <!-- callback -->
 
             <call method="setStopwatch">
-                <argument type="service" id="debug.stopwatch" />
+                <argument type="service" id="debug.stopwatch" on-invalid="null" />
             </call>
         </service>