diff --git a/core/net/src/main/java/org/onlab/onos/net/topology/impl/DefaultTopologyProvider.java b/core/net/src/main/java/org/onlab/onos/net/topology/impl/DefaultTopologyProvider.java
index 7ee6ddd..9631c66 100644
--- a/core/net/src/main/java/org/onlab/onos/net/topology/impl/DefaultTopologyProvider.java
+++ b/core/net/src/main/java/org/onlab/onos/net/topology/impl/DefaultTopologyProvider.java
@@ -23,6 +23,7 @@
 import org.onlab.onos.net.topology.TopologyProviderService;
 import org.slf4j.Logger;
 
+import java.util.Collections;
 import java.util.List;
 import java.util.Timer;
 import java.util.concurrent.ExecutorService;
@@ -88,7 +89,7 @@
         linkService.addListener(linkListener);
 
         isStarted = true;
-        triggerTopologyBuild(null);
+        triggerTopologyBuild(Collections.<Event>emptyList());
         log.info("Started");
     }