diff --git a/OpenSim/Region/CoreModules/World/Estate/XEstateConnector.cs b/OpenSim/Region/CoreModules/World/Estate/XEstateConnector.cs
index 948c8934a9..73e706c339 100644
--- a/OpenSim/Region/CoreModules/World/Estate/XEstateConnector.cs
+++ b/OpenSim/Region/CoreModules/World/Estate/XEstateConnector.cs
@@ -136,15 +136,18 @@ namespace OpenSim.Region.CoreModules.World.Estate
 
             // Handle local regions locally
             //
-            foreach (Scene s in m_EstateModule.Scenes)
+            lock (m_EstateModule.Scenes)
             {
-                if (regions.Contains(s.RegionInfo.RegionID))
+                foreach (Scene s in m_EstateModule.Scenes)
                 {
-                    // All regions in one estate are in the same scope.
-                    // Use that scope.
-                    //
-                    ScopeID = s.RegionInfo.ScopeID;
-                    regions.Remove(s.RegionInfo.RegionID);
+                    if (regions.Contains(s.RegionInfo.RegionID))
+                    {
+                        // All regions in one estate are in the same scope.
+                        // Use that scope.
+                        //
+                        ScopeID = s.RegionInfo.ScopeID;
+                        regions.Remove(s.RegionInfo.RegionID);
+                    }
                 }
             }
 
diff --git a/OpenSim/Region/CoreModules/World/Estate/XEstateModule.cs b/OpenSim/Region/CoreModules/World/Estate/XEstateModule.cs
index 1f099c61ad..f54ab2c13e 100644
--- a/OpenSim/Region/CoreModules/World/Estate/XEstateModule.cs
+++ b/OpenSim/Region/CoreModules/World/Estate/XEstateModule.cs
@@ -93,7 +93,8 @@ namespace OpenSim.Region.CoreModules.World.Estate
 
         public void AddRegion(Scene scene)
         {
-            m_Scenes.Add(scene);
+            lock (m_Scenes)
+                m_Scenes.Add(scene);
 
             scene.EventManager.OnNewClient += OnNewClient;
         }
@@ -111,7 +112,8 @@ namespace OpenSim.Region.CoreModules.World.Estate
         {
             scene.EventManager.OnNewClient -= OnNewClient;
 
-            m_Scenes.Remove(scene);
+            lock (m_Scenes)
+                m_Scenes.Remove(scene);
         }
 
         public string Name