diff --git a/src/server/game/Achievements/AchievementMgr.h b/src/server/game/Achievements/AchievementMgr.h
index 678aa0bcc93..16f4d20614a 100644
--- a/src/server/game/Achievements/AchievementMgr.h
+++ b/src/server/game/Achievements/AchievementMgr.h
@@ -30,6 +30,7 @@
 
 class Unit;
 class Player;
+class Guild;
 class WorldPacket;
 
 struct ModifierTreeNode