diff --git a/src/main/java/net/onrc/onos/registry/controller/StandaloneRegistry.java b/src/main/java/net/onrc/onos/registry/controller/StandaloneRegistry.java
index 7345084..2c220fd 100644
--- a/src/main/java/net/onrc/onos/registry/controller/StandaloneRegistry.java
+++ b/src/main/java/net/onrc/onos/registry/controller/StandaloneRegistry.java
@@ -91,7 +91,7 @@
 
 	@Override
 	public String getControllerForSwitch(long dpid) throws RegistryException {
-		return controllerId;
+		return (switchCallbacks.get(HexString.toHexString(dpid)) != null)? controllerId: null;
 	}
 
 	@Override