diff --git a/src/openrct2/windows/land.c b/src/openrct2/windows/land.c
index 5d864d358e..8dc1199106 100644
--- a/src/openrct2/windows/land.c
+++ b/src/openrct2/windows/land.c
@@ -212,7 +212,7 @@ static void window_land_mousedown(rct_widgetindex widgetIndex, rct_window*w, rct
     sint32 defaultIndex = -1;
     switch (widgetIndex) {
     case WIDX_FLOOR:
-        for (i = 0; i < 14; i++) {
+        for (i = 0; i < TERRAIN_COUNT_REGULAR; i++) {
             gDropdownItemsFormat[i] = -1;
             gDropdownItemsArgs[i] = SPR_FLOOR_TEXTURE_GRASS + FloorTextureOrder[i];
             if (FloorTextureOrder[i] == _selectedFloorTexture)
@@ -223,14 +223,14 @@ static void window_land_mousedown(rct_widgetindex widgetIndex, rct_window*w, rct
             widget->bottom - widget->top,
             w->colours[2],
             0,
-            14,
+            TERRAIN_COUNT_REGULAR,
             47, 36,
-            gAppropriateImageDropdownItemsPerRow[14]
+            gAppropriateImageDropdownItemsPerRow[TERRAIN_COUNT_REGULAR]
         );
         gDropdownDefaultIndex = defaultIndex;
         break;
     case WIDX_WALL:
-        for (i = 0; i < 4; i++) {
+        for (i = 0; i < TERRAIN_EDGE_COUNT; i++) {
             gDropdownItemsFormat[i] = -1;
             gDropdownItemsArgs[i] = SPR_WALL_TEXTURE_ROCK + WallTextureOrder[i];
             if (WallTextureOrder[i] == _selectedWallTexture)
@@ -241,9 +241,9 @@ static void window_land_mousedown(rct_widgetindex widgetIndex, rct_window*w, rct
             widget->bottom - widget->top,
             w->colours[2],
             0,
-            4,
+            TERRAIN_EDGE_COUNT,
             47, 36,
-            gAppropriateImageDropdownItemsPerRow[4]
+            gAppropriateImageDropdownItemsPerRow[TERRAIN_EDGE_COUNT]
         );
         gDropdownDefaultIndex = defaultIndex;
         break;
diff --git a/src/openrct2/windows/mapgen.c b/src/openrct2/windows/mapgen.c
index 0847fea503..2d13049eb2 100644
--- a/src/openrct2/windows/mapgen.c
+++ b/src/openrct2/windows/mapgen.c
@@ -695,7 +695,7 @@ static void window_mapgen_base_mousedown(rct_widgetindex widgetIndex, rct_window
         window_invalidate(w);
         break;
     case WIDX_FLOOR_TEXTURE:
-        for (i = 0; i < 14; i++) {
+        for (i = 0; i < TERRAIN_COUNT_REGULAR; i++) {
             gDropdownItemsFormat[i] = -1;
             gDropdownItemsArgs[i] = SPR_FLOOR_TEXTURE_GRASS + FloorTextureOrder[i];
             if (FloorTextureOrder[i] == _floorTexture)
@@ -706,14 +706,14 @@ static void window_mapgen_base_mousedown(rct_widgetindex widgetIndex, rct_window
             widget->bottom - widget->top,
             w->colours[2],
             0,
-            14,
+            TERRAIN_COUNT_REGULAR,
             47, 36,
-            gAppropriateImageDropdownItemsPerRow[14]
+            gAppropriateImageDropdownItemsPerRow[TERRAIN_COUNT_REGULAR]
         );
         gDropdownDefaultIndex = defaultIndex;
         break;
     case WIDX_WALL_TEXTURE:
-        for (i = 0; i < 4; i++) {
+        for (i = 0; i < TERRAIN_EDGE_COUNT; i++) {
             gDropdownItemsFormat[i] = -1;
             gDropdownItemsArgs[i] = SPR_WALL_TEXTURE_ROCK + WallTextureOrder[i];
             if (WallTextureOrder[i] == _wallTexture)
@@ -724,9 +724,9 @@ static void window_mapgen_base_mousedown(rct_widgetindex widgetIndex, rct_window
             widget->bottom - widget->top,
             w->colours[2],
             0,
-            4,
+            TERRAIN_EDGE_COUNT,
             47, 36,
-            gAppropriateImageDropdownItemsPerRow[4]
+            gAppropriateImageDropdownItemsPerRow[TERRAIN_EDGE_COUNT]
         );
         gDropdownDefaultIndex = defaultIndex;
         break;
@@ -1014,7 +1014,7 @@ static void window_mapgen_simplex_mousedown(rct_widgetindex widgetIndex, rct_win
         window_invalidate(w);
         break;
     case WIDX_SIMPLEX_FLOOR_TEXTURE:
-        for (i = 0; i < 14; i++) {
+        for (i = 0; i < TERRAIN_COUNT_REGULAR; i++) {
             gDropdownItemsFormat[i] = -1;
             gDropdownItemsArgs[i] = SPR_FLOOR_TEXTURE_GRASS + FloorTextureOrder[i];
             if (FloorTextureOrder[i] == _floorTexture)
@@ -1025,14 +1025,14 @@ static void window_mapgen_simplex_mousedown(rct_widgetindex widgetIndex, rct_win
             widget->bottom - widget->top,
             w->colours[2],
             0,
-            14,
+            TERRAIN_COUNT_REGULAR,
             47, 36,
-            gAppropriateImageDropdownItemsPerRow[14]
+            gAppropriateImageDropdownItemsPerRow[TERRAIN_COUNT_REGULAR]
             );
         gDropdownDefaultIndex = defaultIndex;
         break;
     case WIDX_SIMPLEX_WALL_TEXTURE:
-        for (i = 0; i < 4; i++) {
+        for (i = 0; i < TERRAIN_EDGE_COUNT; i++) {
             gDropdownItemsFormat[i] = -1;
             gDropdownItemsArgs[i] = SPR_WALL_TEXTURE_ROCK + WallTextureOrder[i];
             if (WallTextureOrder[i] == _wallTexture)
@@ -1043,9 +1043,9 @@ static void window_mapgen_simplex_mousedown(rct_widgetindex widgetIndex, rct_win
             widget->bottom - widget->top,
             w->colours[2],
             0,
-            4,
+            TERRAIN_EDGE_COUNT,
             47, 36,
-            gAppropriateImageDropdownItemsPerRow[4]
+            gAppropriateImageDropdownItemsPerRow[TERRAIN_EDGE_COUNT]
             );
         gDropdownDefaultIndex = defaultIndex;
         break;
diff --git a/src/openrct2/world/map.h b/src/openrct2/world/map.h
index 085d378401..9a6420e07c 100644
--- a/src/openrct2/world/map.h
+++ b/src/openrct2/world/map.h
@@ -174,7 +174,8 @@ enum {
     TERRAIN_GRID_GREEN,
     TERRAIN_SAND_DARK,
     TERRAIN_SAND_LIGHT,
-    TERRAIN_CHECKERBOARD_INVERTED,
+    TERRAIN_COUNT_REGULAR = 14, // The amount of surface types the user can actually select - what follows are technical types
+    TERRAIN_CHECKERBOARD_INVERTED = 14,
     TERRAIN_UNDERGROUND_VIEW,
 };
 
@@ -182,7 +183,8 @@ enum {
     TERRAIN_EDGE_ROCK,
     TERRAIN_EDGE_WOOD_RED,
     TERRAIN_EDGE_WOOD_BLACK,
-    TERRAIN_EDGE_ICE
+    TERRAIN_EDGE_ICE,
+    TERRAIN_EDGE_COUNT
 };
 
 enum {