diff --git a/src/server/game/Instances/InstanceSaveMgr.h b/src/server/game/Instances/InstanceSaveMgr.h
index b1c685c5a2..4075947789 100755
--- a/src/server/game/Instances/InstanceSaveMgr.h
+++ b/src/server/game/Instances/InstanceSaveMgr.h
@@ -116,12 +116,12 @@ typedef UNORDERED_MAP<uint32 /*PAIR32(map,difficulty)*/,time_t /*resetTime*/> Re
 
 class InstanceSaveManager
 {
-    friend class ACE_Singleton<InstanceSaveManager, ACE_Null_Mutex>;
+    friend class ACE_Singleton<InstanceSaveManager, ACE_Thread_Mutex>;
     friend class InstanceSave;
-    public:
         InstanceSaveManager() : lock_instLists(false) {};
         ~InstanceSaveManager();
 
+    public:
         typedef UNORDERED_MAP<uint32 /*InstanceId*/, InstanceSave*> InstanceSaveHashMap;
 
         /* resetTime is a global propery of each (raid/heroic) map