diff --git a/src/house.h b/src/house.h
index d7bbd1c93bb..0c945da647a 100644
--- a/src/house.h
+++ b/src/house.h
@@ -68,7 +68,7 @@ static_assert(HZB_END == 5);
 
 DECLARE_POSTFIX_INCREMENT(HouseZonesBits)
 
-enum HouseZones {                  ///< Bit  Value       Meaning
+enum HouseZones : uint16_t {        ///< Bit  Value       Meaning
 	HZ_NOZNS             = 0x0000,  ///<       0          This is just to get rid of zeros, meaning none
 	HZ_ZON1              = 1U << HZB_TOWN_EDGE,    ///< 0..4 1,2,4,8,10  which town zones the building can be built in, Zone1 been the further suburb
 	HZ_ZON2              = 1U << HZB_TOWN_OUTSKIRT,
diff --git a/src/newgrf_house.cpp b/src/newgrf_house.cpp
index e30dee8ce78..d61410b5ede 100644
--- a/src/newgrf_house.cpp
+++ b/src/newgrf_house.cpp
@@ -461,7 +461,7 @@ static uint32_t GetDistanceFromNearbyHouse(uint8_t parameter, TileIndex tile, Ho
 		case 0x41: return 0;
 
 		/* Town zone */
-		case 0x42: return FindFirstBit(HouseSpec::Get(this->house_id)->building_availability & HZ_ZONALL); // first available
+		case 0x42: return FindFirstBit<HouseZones>(HouseSpec::Get(this->house_id)->building_availability & HZ_ZONALL); // first available
 
 		/* Terrain type */
 		case 0x43: return _settings_game.game_creation.landscape == LT_ARCTIC && (HouseSpec::Get(house_id)->building_availability & (HZ_SUBARTC_ABOVE | HZ_SUBARTC_BELOW)) == HZ_SUBARTC_ABOVE ? 4 : 0;