diff --git a/src/newgrf_commons.h b/src/newgrf_commons.h
--- a/src/newgrf_commons.h
+++ b/src/newgrf_commons.h
@@ -185,7 +185,7 @@ public:
 	void Add(uint8 local_id, uint32 grfid, uint entity_type);
 	virtual uint16 AddEntityID(byte grf_local_id, uint32 grfid, byte substitute_id);
 
-	uint16 GetGRFID(uint16 entity_id) const;
+	uint32 GetGRFID(uint16 entity_id) const;
 	uint16 GetSubstituteID(uint16 entity_id) const;
 	virtual uint16 GetID(uint8 grf_local_id, uint32 grfid) const;