diff --git a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
index 3347de11ff..907f2bbc50 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/LLUDPServer.cs
@@ -254,7 +254,10 @@ namespace OpenSim.Region.ClientStack.LindenUDP
         void  packet_type_timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
         {
             for (int i = 0; i < 9; ++i)
-                m_log.WarnFormat("OutgoingPacket type {0} count = {1}", i, OutgoingPacket.CatCounts[i]);
+            {
+                int val = Interlocked.Exchange(ref OutgoingPacket.CatCounts[i], 0);
+                m_log.WarnFormat("OutgoingPacket type {0} count = {1}", i, val);
+            }
         }
 
         public new void Stop()
diff --git a/OpenSim/Region/ClientStack/LindenUDP/OutgoingPacket.cs b/OpenSim/Region/ClientStack/LindenUDP/OutgoingPacket.cs
index 90a2e8eaf3..7d780dfd8d 100644
--- a/OpenSim/Region/ClientStack/LindenUDP/OutgoingPacket.cs
+++ b/OpenSim/Region/ClientStack/LindenUDP/OutgoingPacket.cs
@@ -27,7 +27,8 @@
 
 using System;
 using OpenSim.Framework;
-using OpenMetaverse;
+using OpenMetaverse;
+using System.Threading;
 
 namespace OpenSim.Region.ClientStack.LindenUDP
 {
@@ -67,10 +68,10 @@ namespace OpenSim.Region.ClientStack.LindenUDP
             Client = client;
             Buffer = buffer;
             Category = category;
+            int type = (int)category;
             if (category == ThrottleOutPacketType.Unknown)
-                CatCounts[8]++;
-            else
-                CatCounts[(int)category]++;
+                type = 8;
+            Interlocked.Increment(ref OutgoingPacket.CatCounts[type]);
         }
     }
 }