diff --git a/include/constants/map_types.h b/include/constants/map_types.h
index 8d071fd41d..03a3f0a9a0 100755
--- a/include/constants/map_types.h
+++ b/include/constants/map_types.h
@@ -1,14 +1,14 @@
 #ifndef GUARD_CONSTANTS_MAP_TYPES_H
 #define GUARD_CONSTANTS_MAP_TYPES_H
 
-#define MAP_TYPE_UNUSED_1    0
+#define MAP_TYPE_NONE        0
 #define MAP_TYPE_TOWN        1
 #define MAP_TYPE_CITY        2
 #define MAP_TYPE_ROUTE       3
 #define MAP_TYPE_UNDERGROUND 4
 #define MAP_TYPE_UNDERWATER  5
 #define MAP_TYPE_OCEAN_ROUTE 6
-#define MAP_TYPE_UNUSED_2    7
+#define MAP_TYPE_UNKNOWN     7 // Not used by any map.
 #define MAP_TYPE_INDOOR      8
 #define MAP_TYPE_SECRET_BASE 9
 
diff --git a/src/fldeff_flash.c b/src/fldeff_flash.c
index e2497ca950..3cb91d4b10 100644
--- a/src/fldeff_flash.c
+++ b/src/fldeff_flash.c
@@ -50,7 +50,7 @@ static const struct FlashStruct sTransitionTypes[] =
     {MAP_TYPE_ROUTE,       MAP_TYPE_UNDERGROUND,  TRUE, FALSE, DoEnterCaveTransition},
     {MAP_TYPE_UNDERWATER,  MAP_TYPE_UNDERGROUND,  TRUE, FALSE, DoEnterCaveTransition},
     {MAP_TYPE_OCEAN_ROUTE, MAP_TYPE_UNDERGROUND,  TRUE, FALSE, DoEnterCaveTransition},
-    {MAP_TYPE_UNUSED_2,    MAP_TYPE_UNDERGROUND,  TRUE, FALSE, DoEnterCaveTransition},
+    {MAP_TYPE_UNKNOWN,     MAP_TYPE_UNDERGROUND,  TRUE, FALSE, DoEnterCaveTransition},
     {MAP_TYPE_INDOOR,      MAP_TYPE_UNDERGROUND,  TRUE, FALSE, DoEnterCaveTransition},
     {MAP_TYPE_SECRET_BASE, MAP_TYPE_UNDERGROUND,  TRUE, FALSE, DoEnterCaveTransition},
     {MAP_TYPE_UNDERGROUND, MAP_TYPE_TOWN,        FALSE,  TRUE, DoExitCaveTransition},
@@ -58,7 +58,7 @@ static const struct FlashStruct sTransitionTypes[] =
     {MAP_TYPE_UNDERGROUND, MAP_TYPE_ROUTE,       FALSE,  TRUE, DoExitCaveTransition},
     {MAP_TYPE_UNDERGROUND, MAP_TYPE_UNDERWATER,  FALSE,  TRUE, DoExitCaveTransition},
     {MAP_TYPE_UNDERGROUND, MAP_TYPE_OCEAN_ROUTE, FALSE,  TRUE, DoExitCaveTransition},
-    {MAP_TYPE_UNDERGROUND, MAP_TYPE_UNUSED_2,    FALSE,  TRUE, DoExitCaveTransition},
+    {MAP_TYPE_UNDERGROUND, MAP_TYPE_UNKNOWN,     FALSE,  TRUE, DoExitCaveTransition},
     {MAP_TYPE_UNDERGROUND, MAP_TYPE_INDOOR,      FALSE,  TRUE, DoExitCaveTransition},
     {MAP_TYPE_UNDERGROUND, MAP_TYPE_SECRET_BASE, FALSE,  TRUE, DoExitCaveTransition},
     {},
diff --git a/src/region_map.c b/src/region_map.c
index 394f4cc911..0ee30527f3 100644
--- a/src/region_map.c
+++ b/src/region_map.c
@@ -1003,7 +1003,7 @@ static void InitMapBasedOnPlayerLocation(void)
             gRegionMap->playerIsInCave = TRUE;
         break;
     case MAP_TYPE_UNDERGROUND:
-    case MAP_TYPE_UNUSED_2:
+    case MAP_TYPE_UNKNOWN:
         if (gMapHeader.flags & MAP_ALLOW_ESCAPING)
         {
             mapHeader = Overworld_GetMapHeaderByGroupAndId(gSaveBlock1Ptr->escapeWarp.mapGroup, gSaveBlock1Ptr->escapeWarp.mapNum);