diff --git a/OpenSim/Framework/BlockingQueue.cs b/OpenSim/Framework/BlockingQueue.cs
index 3ff3dac596..dd6d866e39 100644
--- a/OpenSim/Framework/BlockingQueue.cs
+++ b/OpenSim/Framework/BlockingQueue.cs
@@ -59,7 +59,10 @@ namespace OpenSim.Framework
 
         public bool Contains(T item)
         {
-            return m_queue.Contains(item);
+            lock (m_queueSync)
+            {
+                return m_queue.Contains(item);
+            }
         }
     }
 }
\ No newline at end of file