diff --git a/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs b/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs
index c9c4753195..c6393ed554 100644
--- a/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/LSL_Types.cs
@@ -512,7 +512,7 @@ namespace OpenSim.Region.ScriptEngine.Shared
                         else if (o is LSL_Types.LSLFloat)
                             size += 8;
                         else if (o is LSL_Types.LSLString)
-                            size += ((LSL_Types.LSLString)o).m_string.Length;
+                            size += ((LSL_Types.LSLString)o).m_string == null ? 0 : ((LSL_Types.LSLString)o).m_string.Length;
                         else if (o is LSL_Types.key)
                             size += ((LSL_Types.key)o).value.Length;
                         else if (o is LSL_Types.Vector3)