diff --git a/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java b/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java
index b3d85ad..0e03767 100644
--- a/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java
+++ b/net/api/src/main/java/org/onlab/onos/net/topology/TopologyProviderService.java
@@ -1,7 +1,10 @@
 package org.onlab.onos.net.topology;
 
+import org.onlab.onos.event.Event;
 import org.onlab.onos.net.provider.ProviderService;
 
+import java.util.List;
+
 /**
  * Means for injecting topology information into the core.
  */
@@ -14,7 +17,9 @@
      * Signals the core that some aspect of the topology has changed.
      *
      * @param topoDescription information about topology
+     * @param reasons         events that triggered topology change
      */
-    void topologyChanged(TopologyDescription topoDescription);
+    void topologyChanged(TopologyDescription topoDescription,
+                         List<Event> reasons);
 
 }