diff --git a/src/newgrf.cpp b/src/newgrf.cpp
index ade7c00..de7a4e7 100644
--- a/src/newgrf.cpp
+++ b/src/newgrf.cpp
@@ -4262,7 +4262,7 @@ static ChangeInfoResult RoadTypeChangeInfo(uint id, int numinfo, int prop, ByteR
        }
 
        for (int i = 0; i < numinfo; i++) {
-               RoadTypeIdentifier rtid = RoadTypeIdentifier(_cur.grffile->roadtype_map[basetype][id + i]);
+               RoadTypeIdentifier rtid = RoadTypeIdentifier(basetype, (RoadSubType)_cur.grffile->roadtype_map[basetype][id + i]);
                if (!rtid.IsValid()) return CIR_INVALID_ID;
 
                RoadtypeInfo *rti = &_roadtypes[basetype][rtid.subtype];