diff --git a/src/viewport.cpp b/src/viewport.cpp
index f283a8dfb7..431cc6637f 100644
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -1931,7 +1931,7 @@ static inline uint32 ViewportMapGetColourVegetation(const TileIndex tile, TileTy
 		case MP_WATER:
 			if (is_32bpp) {
 				uint slope_index = 0;
-				if (IsTileType(t, MP_WATER) && GetWaterTileType(tile) != WATER_TILE_COAST) GET_SLOPE_INDEX(slope_index);
+				if (IsTileType(tile, MP_WATER) && GetWaterTileType(tile) != WATER_TILE_COAST) GET_SLOPE_INDEX(slope_index);
 				return _vp_map_water_colour[slope_index];
 			}
 			/* FALL THROUGH */
@@ -1969,7 +1969,7 @@ static inline uint32 ViewportMapGetColourIndustries(const TileIndex tile, const
 
 	if (is_32bpp && t2 == MP_WATER) {
 		uint slope_index = 0;
-		if (t != MP_INDUSTRY && IsTileType(t, MP_WATER) && GetWaterTileType(tile) != WATER_TILE_COAST) GET_SLOPE_INDEX(slope_index); ///< Ignore industry on water not shown on map.
+		if (t != MP_INDUSTRY && IsTileType(tile, MP_WATER) && GetWaterTileType(tile) != WATER_TILE_COAST) GET_SLOPE_INDEX(slope_index); ///< Ignore industry on water not shown on map.
 		return _vp_map_water_colour[slope_index];
 	}
 
@@ -2000,7 +2000,7 @@ static inline uint32 ViewportMapGetColourOwner(const TileIndex tile, TileType t,
 		if (t == MP_WATER) {
 			if (is_32bpp) {
 				uint slope_index = 0;
-				if (IsTileType(t, MP_WATER) && GetWaterTileType(tile) != WATER_TILE_COAST) GET_SLOPE_INDEX(slope_index);
+				if (IsTileType(tile, MP_WATER) && GetWaterTileType(tile) != WATER_TILE_COAST) GET_SLOPE_INDEX(slope_index);
 				return _vp_map_water_colour[slope_index];
 			} else {
 				return PC_WATER;