diff --git a/src/clear_cmd.cpp b/src/clear_cmd.cpp
index a47cda5181..c093ecaf64 100644
--- a/src/clear_cmd.cpp
+++ b/src/clear_cmd.cpp
@@ -25,13 +25,15 @@
 
 static CommandCost ClearTile_Clear(TileIndex tile, DoCommandFlags flags)
 {
-	static constexpr Price clear_price_table[] = {
-		Price::ClearGrass,
-		Price::ClearRough,
-		Price::ClearRocks,
-		Price::ClearFields,
-		Price::ClearRough,
-		Price::ClearRough,
+	static constexpr Price clear_price_table[to_underlying(ClearGround::MaxSize)] = {
+		Price::ClearGrass, // Base price for clearing grass.
+		Price::ClearRough, // Base price for clearing rough land.
+		Price::ClearRocks, // Base price for clearing rocks.
+		Price::ClearFields, // Base price for clearing fields.
+		Price::ClearRough, // Unused.
+		Price::ClearRough, // Base price for clearing desert.
+		Price::ClearRough, // Unused.
+		Price::ClearRough, // Unused.
 	};
 	CommandCost price(EXPENSES_CONSTRUCTION);
 
@@ -154,6 +156,9 @@ static void DrawTile_Clear(TileInfo *ti)
 		case ClearGround::Desert:
 			DrawGroundSprite(_clear_land_sprites_snow_desert[GetClearDensity(ti->tile)] + SlopeToSpriteOffset(ti->tileh), PAL_NONE);
 			break;
+
+		default:
+			NOT_REACHED();
 	}
 
 	DrawBridgeMiddle(ti, {});
@@ -370,13 +375,15 @@ static TrackStatus GetTileTrackStatus_Clear(TileIndex, TransportType, uint, Diag
 static void GetTileDesc_Clear(TileIndex tile, TileDesc &td)
 {
 	/* Each pair holds a normal and a snowy ClearGround description. */
-	static constexpr std::pair<StringID, StringID> clear_land_str[] = {
-		{STR_LAI_CLEAR_DESCRIPTION_GRASS,      STR_LAI_CLEAR_DESCRIPTION_SNOWY_GRASS},
-		{STR_LAI_CLEAR_DESCRIPTION_ROUGH_LAND, STR_LAI_CLEAR_DESCRIPTION_SNOWY_ROUGH_LAND},
-		{STR_LAI_CLEAR_DESCRIPTION_ROCKS,      STR_LAI_CLEAR_DESCRIPTION_SNOWY_ROCKS},
-		{STR_LAI_CLEAR_DESCRIPTION_FIELDS,     STR_EMPTY},
+	static constexpr std::pair<StringID, StringID> clear_land_str[to_underlying(ClearGround::MaxSize)] = {
+		{STR_LAI_CLEAR_DESCRIPTION_GRASS,      STR_LAI_CLEAR_DESCRIPTION_SNOWY_GRASS}, // Description for grass.
+		{STR_LAI_CLEAR_DESCRIPTION_ROUGH_LAND, STR_LAI_CLEAR_DESCRIPTION_SNOWY_ROUGH_LAND}, // Description for rough land.
+		{STR_LAI_CLEAR_DESCRIPTION_ROCKS,      STR_LAI_CLEAR_DESCRIPTION_SNOWY_ROCKS}, // Description for rocks.
+		{STR_LAI_CLEAR_DESCRIPTION_FIELDS,     STR_EMPTY}, // Description for fields.
+		{STR_EMPTY,                            STR_EMPTY}, // unused entry does not appear in the map.
+		{STR_LAI_CLEAR_DESCRIPTION_DESERT,     STR_EMPTY}, // Description for desert.
+		{STR_EMPTY,                            STR_EMPTY}, // unused entry does not appear in the map.
 		{STR_EMPTY,                            STR_EMPTY}, // unused entry does not appear in the map.
-		{STR_LAI_CLEAR_DESCRIPTION_DESERT,     STR_EMPTY},
 	};
 
 	if (!IsSnowTile(tile) && IsClearGround(tile, ClearGround::Grass) && GetClearDensity(tile) == 0) {
diff --git a/src/clear_map.h b/src/clear_map.h
index 5bc6d1df86..6153a8949b 100644
--- a/src/clear_map.h
+++ b/src/clear_map.h
@@ -13,6 +13,8 @@
 #include "bridge_map.h"
 #include "industry_type.h"
 
+static constexpr size_t CLEAR_GROUND_BITS = 3; ///< How many bits in map array are dedicated for clear ground type.
+
 /**
  * Ground types. Valid densities in comments after the enum.
  */
@@ -22,8 +24,12 @@ enum class ClearGround : uint8_t {
 	Rocks = 2, ///< Rocks with snow transition (0-3)
 	Fields = 3, ///< Farm fields (3)
 	Desert = 5, ///< Desert with transition (1,3)
+
+	End, ///< End marker.
+	MaxSize = 1U << CLEAR_GROUND_BITS, ///< The maximum possible number of clear ground types to be stored in map.
 };
 
+static_assert(ClearGround::End <= ClearGround::MaxSize);
 
 /**
  * Test if a tile is covered with snow.
@@ -46,7 +52,7 @@ inline bool IsSnowTile(Tile t)
 inline ClearGround GetClearGround(Tile t)
 {
 	assert(IsTileType(t, TileType::Clear));
-	return static_cast<ClearGround>(GB(t.m5(), 2, 3));
+	return static_cast<ClearGround>(GB(t.m5(), 2, CLEAR_GROUND_BITS));
 }
 
 /**
diff --git a/src/smallmap_gui.cpp b/src/smallmap_gui.cpp
index 19b645a076..cecfa3ca23 100644
--- a/src/smallmap_gui.cpp
+++ b/src/smallmap_gui.cpp
@@ -526,7 +526,8 @@ static inline uint32_t GetSmallMapLinkStatsPixels(TileIndex tile, TileType t)
 	return _smallmap_show_heightmap ? GetSmallMapContoursPixels(tile, t) : GetSmallMapRoutesPixels(tile, t);
 }
 
-static const uint32_t _vegetation_clear_bits[] = {
+/** Lookup table of minimap colours to use for each ClearGround type. */
+static constexpr uint32_t _vegetation_clear_bits[to_underlying(ClearGround::MaxSize)] = {
 	MKCOLOUR_XXXX(PC_GRASS_LAND), ///< full grass
 	MKCOLOUR_XXXX(PC_ROUGH_LAND), ///< rough land
 	MKCOLOUR_XXXX(PC_GREY),       ///< rocks