diff --git a/game/shared/igamesystem.h b/game/shared/igamesystem.h
index e4eb9ef6..de300f7a 100644
--- a/game/shared/igamesystem.h
+++ b/game/shared/igamesystem.h
@@ -47,6 +47,7 @@ class ISpawnGroupPrerequisiteRegistry;
 class IEntityPrecacheConfiguration;
 struct EngineLoopState_t;
 struct EntitySpawnInfo_t;
+struct Entity2Networkable_t;
 
 #define DECLARE_GAME_SYSTEM() \
 	virtual void YouForgot_DECLARE_GAME_SYSTEM_InYourClassDefinition() override {}; \