diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
index 35134d6a23..a4b8944b13 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
@@ -3651,7 +3651,8 @@ namespace OpenSim.Region.Framework.Scenes
                     if (atRotTargets.Count > 0)
                     {
                         uint[] localids = new uint[0];
-                        lock (m_parts)
+                        lockPartsForRead(true);
+                        try
                         {
                             localids = new uint[m_parts.Count];
                             int cntr = 0;
@@ -3661,6 +3662,10 @@ namespace OpenSim.Region.Framework.Scenes
                                 cntr++;
                             }
                         }
+                        finally
+                        {
+                            lockPartsForRead(false);
+                        }
 
                         for (int ctr = 0; ctr < localids.Length; ctr++)
                         {
@@ -3679,7 +3684,8 @@ namespace OpenSim.Region.Framework.Scenes
                     {
                         //trigger not_at_target
                         uint[] localids = new uint[0];
-                        lock (m_parts)
+                        lockPartsForRead(true);
+                        try
                         {
                             localids = new uint[m_parts.Count];
                             int cntr = 0;
@@ -3689,6 +3695,10 @@ namespace OpenSim.Region.Framework.Scenes
                                 cntr++;
                             }
                         }
+                        finally
+                        {
+                            lockPartsForRead(false);
+                        }
 
                         for (int ctr = 0; ctr < localids.Length; ctr++)
                         {