diff --git a/newgrf_text.h b/newgrf_text.h
--- a/newgrf_text.h
+++ b/newgrf_text.h
@@ -30,7 +30,7 @@ typedef struct GRFTextEntry {
 } GRFTextEntry;
 
 
-StringID AddGRFString(uint32 grfid, uint16 stringid, byte langid, const char *text_to_add);
+StringID AddGRFString(uint32 grfid, uint16 stringid, byte langid, bool new_scheme, const char *text_to_add);
 StringID GetGRFStringID(uint32 grfid, uint16 stringid);
 char *GetGRFString(char *buff, uint16 stringid);
 void CleanUpStrings(void);