diff --git a/src/newgrf_station.cpp b/src/newgrf_station.cpp
--- a/src/newgrf_station.cpp
+++ b/src/newgrf_station.cpp
@@ -649,7 +649,7 @@ uint16_t GetStationCallback(CallbackID c
  */
 CommandCost PerformStationTileSlopeCheck(TileIndex north_tile, TileIndex cur_tile, const StationSpec *statspec, Axis axis, byte plat_len, byte numtracks)
 {
-	TileIndexDiff diff = cur_tile - north_tile;
+	TileIndex diff = cur_tile - north_tile;
 	Slope slope = GetTileSlope(cur_tile);
 
 	StationResolverObject object(statspec, nullptr, cur_tile, CBID_STATION_LAND_SLOPE_CHECK,