diff --git a/OpenSim/Services/Connectors/Simulation/SimulationServiceConnector.cs b/OpenSim/Services/Connectors/Simulation/SimulationServiceConnector.cs
index c45e312a49..65f01b39c5 100644
--- a/OpenSim/Services/Connectors/Simulation/SimulationServiceConnector.cs
+++ b/OpenSim/Services/Connectors/Simulation/SimulationServiceConnector.cs
@@ -215,8 +215,11 @@ namespace OpenSim.Services.Connectors.Simulation
             }
             // we get here iff success == false
             // blacklist sim for 2 minutes
-            _failedSims.AddOrUpdate(destination.ServerURI, true, 120);
-            m_updateAgentQueue.Clear();
+            lock (m_updateAgentQueue)
+            {
+                _failedSims.AddOrUpdate(destination.ServerURI, true, 120);
+                m_updateAgentQueue.Remove(uri);
+            }
             return false;
         }