diff --git a/src/server/scripts/Kalimdor/TempleOfAhnQiraj/boss_cthun.cpp b/src/server/scripts/Kalimdor/TempleOfAhnQiraj/boss_cthun.cpp
index 77d4d4d85..e5e6fab05 100644
--- a/src/server/scripts/Kalimdor/TempleOfAhnQiraj/boss_cthun.cpp
+++ b/src/server/scripts/Kalimdor/TempleOfAhnQiraj/boss_cthun.cpp
@@ -545,6 +545,8 @@ struct boss_cthun : public BossAI
         {
             eye->DespawnOrUnsummon();
         }
+
+        instance->SetData(DATA_CTHUN_PHASE, PHASE_CTHUN_DONE);
     }
 
     void SummonedCreatureDies(Creature* creature, Unit* /*killer*/) override