diff --git a/giraph-core/src/main/java/org/apache/giraph/graph/GraphTaskManager.java b/giraph-core/src/main/java/org/apache/giraph/graph/GraphTaskManager.java
index 2e35bcd..8bc73d3 100644
--- a/giraph-core/src/main/java/org/apache/giraph/graph/GraphTaskManager.java
+++ b/giraph-core/src/main/java/org/apache/giraph/graph/GraphTaskManager.java
@@ -642,7 +642,9 @@
                   info.getGcCause() + ", duration = " +
                   info.getGcInfo().getDuration() + "ms");
             }
-            gcTimeMetric.inc(info.getGcInfo().getDuration());
+            if (gcTimeMetrics != null) {
+              gcTimeMetric.inc(info.getGcInfo().getDuration());
+            }
             GiraphMetrics.get().getGcTracker().gcOccurred(info.getGcInfo());
             for (GcObserver gcObserver : gcObservers) {
               gcObserver.gcOccurred(info);