diff --git a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
index 3b12fdb..abede47 100644
--- a/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
+++ b/providers/openflow/device/src/main/java/org/onosproject/provider/of/device/impl/OpenFlowDeviceProvider.java
@@ -788,7 +788,7 @@
                             OFPortStatsReply portStatsReply = (OFPortStatsReply) msg;
                             List<OFPortStatsEntry> portStatsReplyList = portStatsReplies.get(dpid);
                             if (portStatsReplyList == null) {
-                                portStatsReplyList = Lists.newArrayList();
+                                portStatsReplyList = Lists.newCopyOnWriteArrayList();
                             }
                             portStatsReplyList.addAll(portStatsReply.getEntries());
                             portStatsReplies.put(dpid, portStatsReplyList);