diff --git a/core/test/java/com/codingchili/core/context/SystemContextTest.java b/core/test/java/com/codingchili/core/context/SystemContextTest.java
index dad093c2..04454ef9 100644
--- a/core/test/java/com/codingchili/core/context/SystemContextTest.java
+++ b/core/test/java/com/codingchili/core/context/SystemContextTest.java
@@ -25,7 +25,7 @@
 @RunWith(VertxUnitRunner.class)
 public class SystemContextTest {
     private SystemContext context;
-    private OnMetricListener listener;
+    private OnMetricListener listener = metrics -> { };
     private SystemSettings settings;
 
     @Rule