diff --git a/core/net/src/test/java/org/onlab/onos/cluster/impl/MastershipManagerTest.java b/core/net/src/test/java/org/onlab/onos/cluster/impl/MastershipManagerTest.java
index 29b4ddf..e6cf542 100644
--- a/core/net/src/test/java/org/onlab/onos/cluster/impl/MastershipManagerTest.java
+++ b/core/net/src/test/java/org/onlab/onos/cluster/impl/MastershipManagerTest.java
@@ -18,6 +18,8 @@
 import org.onlab.onos.store.trivial.impl.SimpleMastershipStore;
 import org.onlab.packet.IpPrefix;
 
+import com.google.common.collect.Sets;
+
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.onlab.onos.net.MastershipRole.*;
@@ -143,7 +145,7 @@
 
         @Override
         public Set<ControllerNode> getNodes() {
-            return null;
+            return Sets.newHashSet();
         }
 
         @Override