diff --git a/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java b/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java
index 4feaa8e..d447580 100644
--- a/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java
+++ b/src/main/java/net/onrc/onos/ofcontroller/topology/TopologyManager.java
@@ -211,7 +211,7 @@
      */
     @Override
     public void dropTopology(Topology topology) {
-	topology = null;
+    // nothing to do
     }
 
     /**