diff --git a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
index f27a1221be..8f4e840c67 100644
--- a/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
+++ b/OpenSim/Region/ScriptEngine/Shared/Api/Implementation/LSL_Api.cs
@@ -816,8 +816,10 @@ namespace OpenSim.Region.ScriptEngine.Shared.Api
         public LSL_Float llFrand(double mag)
         {
             m_host.AddScriptLPS(1);
-
-            return Util.RandomClass.NextDouble() * mag;
+            lock (Util.RandomClass)
+            {
+				return Util.RandomClass.NextDouble() * mag;
+			}
         }
 
         public LSL_Integer llFloor(double f)