diff --git a/OpenSim/Region/CoreModules/Scripting/WorldComm/WorldCommModule.cs b/OpenSim/Region/CoreModules/Scripting/WorldComm/WorldCommModule.cs
index d4a28e2399..60df2e7273 100644
--- a/OpenSim/Region/CoreModules/Scripting/WorldComm/WorldCommModule.cs
+++ b/OpenSim/Region/CoreModules/Scripting/WorldComm/WorldCommModule.cs
@@ -602,9 +602,12 @@ namespace OpenSim.Region.CoreModules.Scripting.WorldComm
                 ListenerInfo info =
                         ListenerInfo.FromData(localID, itemID, hostID, item);
 
-                if (!m_listeners.ContainsKey((int)item[2]))
-                    m_listeners.Add((int)item[2], new List<ListenerInfo>());
-                m_listeners[(int)item[2]].Add(info);
+                lock (m_listeners)
+                {
+                    if (!m_listeners.ContainsKey((int)item[2]))
+                        m_listeners.Add((int)item[2], new List<ListenerInfo>());
+                    m_listeners[(int)item[2]].Add(info);
+                }
 
                 idx+=6;
             }
diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/Plugins/Timer.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/Plugins/Timer.cs
index 0716d4587c..eeb59d9877 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/Plugins/Timer.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/Plugins/Timer.cs
@@ -166,7 +166,10 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api.Plugins
                 ts.next = DateTime.Now.Ticks + (long)data[idx+1];
                 idx += 2;
 
-                Timers.Add(MakeTimerKey(localID,itemID), ts);
+                lock (TimerListLock)
+                {
+                    Timers.Add(MakeTimerKey(localID, itemID), ts);
+                }
             }
         }
     }