diff --git a/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java b/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java
index b87d37b..2801f12 100644
--- a/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java
+++ b/providers/openflow/group/src/main/java/org/onosproject/provider/of/group/impl/OpenFlowGroupProvider.java
@@ -353,10 +353,12 @@
                 return;
             }
             if (isGroupSupported(sw)) {
-                GroupStatsCollector gsc = new GroupStatsCollector(
-                        controller.getSwitch(dpid), POLL_INTERVAL);
+                GroupStatsCollector gsc = new GroupStatsCollector(sw, POLL_INTERVAL);
                 gsc.start();
-                collectors.put(dpid, gsc);
+                GroupStatsCollector prevGsc = collectors.put(dpid, gsc);
+                if (prevGsc != null) {
+                    prevGsc.stop();
+                }
             }
 
             //figure out race condition