diff --git a/src/spritecache.cpp b/src/spritecache.cpp
--- a/src/spritecache.cpp
+++ b/src/spritecache.cpp
@@ -162,7 +162,7 @@ bool SpriteExists(SpriteID id)
  */
 SpriteType GetSpriteType(SpriteID sprite)
 {
-	if (!SpriteExists(sprite)) return ST_INVALID;
+	if (!SpriteExists(sprite)) return SpriteType::Invalid;
 	return GetSpriteCache(sprite)->type;
 }
 
@@ -461,8 +461,8 @@ static void *ReadSprite(const SpriteCach
 	SpriteFile &file = *sc->file;
 	size_t file_pos = sc->file_pos;
 
-	assert(sprite_type != ST_RECOLOUR);
-	assert(IsMapgenSpriteID(id) == (sprite_type == ST_MAPGEN));
+	assert(sprite_type != SpriteType::Recolour);
+	assert(IsMapgenSpriteID(id) == (sprite_type == SpriteType::MapGen));
 	assert(sc->type == sprite_type);
 
 	Debug(sprite, 9, "Load sprite {}", id);
@@ -472,7 +472,7 @@ static void *ReadSprite(const SpriteCach
 	sprite[ZOOM_LVL_NORMAL].type = sprite_type;
 
 	SpriteLoaderGrf sprite_loader(file.GetContainerVersion());
-	if (sprite_type != ST_MAPGEN && encoder->Is32BppSupported()) {
+	if (sprite_type != SpriteType::MapGen && encoder->Is32BppSupported()) {
 		/* Try for 32bpp sprites first. */
 		sprite_avail = sprite_loader.LoadSprite(sprite, file, file_pos, sprite_type, true, sc->control_flags);
 	}
@@ -481,12 +481,12 @@ static void *ReadSprite(const SpriteCach
 	}
 
 	if (sprite_avail == 0) {
-		if (sprite_type == ST_MAPGEN) return nullptr;
+		if (sprite_type == SpriteType::MapGen) return nullptr;
 		if (id == SPR_IMG_QUERY) usererror("Okay... something went horribly wrong. I couldn't load the fallback sprite. What should I do?");
-		return (void*)GetRawSprite(SPR_IMG_QUERY, ST_NORMAL, allocator, encoder);
+		return (void*)GetRawSprite(SPR_IMG_QUERY, SpriteType::Normal, allocator, encoder);
 	}
 
-	if (sprite_type == ST_MAPGEN) {
+	if (sprite_type == SpriteType::MapGen) {
 		/* Ugly hack to work around the problem that the old landscape
 		 *  generator assumes that those sprites are stored uncompressed in
 		 *  the memory, and they are only read directly by the code, never
@@ -516,10 +516,10 @@ static void *ReadSprite(const SpriteCach
 
 	if (!ResizeSprites(sprite, sprite_avail, encoder)) {
 		if (id == SPR_IMG_QUERY) usererror("Okay... something went horribly wrong. I couldn't resize the fallback sprite. What should I do?");
-		return (void*)GetRawSprite(SPR_IMG_QUERY, ST_NORMAL, allocator, encoder);
+		return (void*)GetRawSprite(SPR_IMG_QUERY, SpriteType::Normal, allocator, encoder);
 	}
 
-	if (sprite->type == ST_FONT && ZOOM_LVL_GUI != ZOOM_LVL_NORMAL) {
+	if (sprite->type == SpriteType::Font && ZOOM_LVL_GUI != ZOOM_LVL_NORMAL) {
 		/* Make ZOOM_LVL_NORMAL be ZOOM_LVL_GUI */
 		sprite[ZOOM_LVL_NORMAL].width  = sprite[ZOOM_LVL_GUI].width;
 		sprite[ZOOM_LVL_NORMAL].height = sprite[ZOOM_LVL_GUI].height;
@@ -629,7 +629,7 @@ bool LoadNextSprite(int load_index, Spri
 			file.ReadByte();
 			return false;
 		}
-		type = ST_RECOLOUR;
+		type = SpriteType::Recolour;
 		data = ReadRecolourSprite(file, num);
 	} else if (file.GetContainerVersion() >= 2 && grf_type == 0xFD) {
 		if (num != 4) {
@@ -645,15 +645,15 @@ bool LoadNextSprite(int load_index, Spri
 		} else {
 			file_pos = SIZE_MAX;
 		}
-		type = ST_NORMAL;
+		type = SpriteType::Normal;
 	} else {
 		file.SkipBytes(7);
-		type = SkipSpriteData(file, grf_type, num - 8) ? ST_NORMAL : ST_INVALID;
+		type = SkipSpriteData(file, grf_type, num - 8) ? SpriteType::Normal : SpriteType::Invalid;
 		/* Inline sprites are not supported for container version >= 2. */
 		if (file.GetContainerVersion() >= 2) return false;
 	}
 
-	if (type == ST_INVALID) return false;
+	if (type == SpriteType::Invalid) return false;
 
 	if (load_index >= MAX_SPRITES) {
 		usererror("Tried to load too many sprites (#%d; max %d)", load_index, MAX_SPRITES);
@@ -662,8 +662,8 @@ bool LoadNextSprite(int load_index, Spri
 	bool is_mapgen = IsMapgenSpriteID(load_index);
 
 	if (is_mapgen) {
-		if (type != ST_NORMAL) usererror("Uhm, would you be so kind not to load a NewGRF that changes the type of the map generator sprites?");
-		type = ST_MAPGEN;
+		if (type != SpriteType::Normal) usererror("Uhm, would you be so kind not to load a NewGRF that changes the type of the map generator sprites?");
+		type = SpriteType::MapGen;
 	}
 
 	SpriteCache *sc = AllocateSpriteCache(load_index);
@@ -828,7 +828,7 @@ static void DeleteEntryFromSpriteCache()
 	cur_lru = 0xffff;
 	for (SpriteID i = 0; i != _spritecache_items; i++) {
 		SpriteCache *sc = GetSpriteCache(i);
-		if (sc->type != ST_RECOLOUR && sc->ptr != nullptr && sc->lru < cur_lru) {
+		if (sc->type != SpriteType::Recolour && sc->ptr != nullptr && sc->lru < cur_lru) {
 			cur_lru = sc->lru;
 			best = i;
 		}
@@ -888,7 +888,7 @@ void *SimpleSpriteAlloc(size_t size)
 
 /**
  * Handles the case when a sprite of different type is requested than is present in the SpriteCache.
- * For ST_FONT sprites, it is normal. In other cases, default sprite is loaded instead.
+ * For SpriteType::Font sprites, it is normal. In other cases, default sprite is loaded instead.
  * @param sprite ID of loaded sprite
  * @param requested requested sprite type
  * @param sc the currently known sprite cache for the requested sprite
@@ -898,33 +898,33 @@ void *SimpleSpriteAlloc(size_t size)
 static void *HandleInvalidSpriteRequest(SpriteID sprite, SpriteType requested, SpriteCache *sc, AllocatorProc *allocator)
 {
 	static const char * const sprite_types[] = {
-		"normal",        // ST_NORMAL
-		"map generator", // ST_MAPGEN
-		"character",     // ST_FONT
-		"recolour",      // ST_RECOLOUR
+		"normal",        // SpriteType::Normal
+		"map generator", // SpriteType::MapGen
+		"character",     // SpriteType::Font
+		"recolour",      // SpriteType::Recolour
 	};
 
 	SpriteType available = sc->type;
-	if (requested == ST_FONT && available == ST_NORMAL) {
-		if (sc->ptr == nullptr) sc->type = ST_FONT;
+	if (requested == SpriteType::Font && available == SpriteType::Normal) {
+		if (sc->ptr == nullptr) sc->type = SpriteType::Font;
 		return GetRawSprite(sprite, sc->type, allocator);
 	}
 
 	byte warning_level = sc->warned ? 6 : 0;
 	sc->warned = true;
-	Debug(sprite, warning_level, "Tried to load {} sprite #{} as a {} sprite. Probable cause: NewGRF interference", sprite_types[available], sprite, sprite_types[requested]);
+	Debug(sprite, warning_level, "Tried to load {} sprite #{} as a {} sprite. Probable cause: NewGRF interference", sprite_types[static_cast<byte>(available)], sprite, sprite_types[static_cast<byte>(requested)]);
 
 	switch (requested) {
-		case ST_NORMAL:
+		case SpriteType::Normal:
 			if (sprite == SPR_IMG_QUERY) usererror("Uhm, would you be so kind not to load a NewGRF that makes the 'query' sprite a non-normal sprite?");
 			FALLTHROUGH;
-		case ST_FONT:
-			return GetRawSprite(SPR_IMG_QUERY, ST_NORMAL, allocator);
-		case ST_RECOLOUR:
+		case SpriteType::Font:
+			return GetRawSprite(SPR_IMG_QUERY, SpriteType::Normal, allocator);
+		case SpriteType::Recolour:
 			if (sprite == PALETTE_TO_DARK_BLUE) usererror("Uhm, would you be so kind not to load a NewGRF that makes the 'PALETTE_TO_DARK_BLUE' sprite a non-remap sprite?");
-			return GetRawSprite(PALETTE_TO_DARK_BLUE, ST_RECOLOUR, allocator);
-		case ST_MAPGEN:
-			/* this shouldn't happen, overriding of ST_MAPGEN sprites is checked in LoadNextSprite()
+			return GetRawSprite(PALETTE_TO_DARK_BLUE, SpriteType::Recolour, allocator);
+		case SpriteType::MapGen:
+			/* this shouldn't happen, overriding of SpriteType::MapGen sprites is checked in LoadNextSprite()
 			 * (the only case the check fails is when these sprites weren't even loaded...) */
 		default:
 			NOT_REACHED();
@@ -942,8 +942,8 @@ static void *HandleInvalidSpriteRequest(
  */
 void *GetRawSprite(SpriteID sprite, SpriteType type, AllocatorProc *allocator, SpriteEncoder *encoder)
 {
-	assert(type != ST_MAPGEN || IsMapgenSpriteID(sprite));
-	assert(type < ST_INVALID);
+	assert(type != SpriteType::MapGen || IsMapgenSpriteID(sprite));
+	assert(type < SpriteType::Invalid);
 
 	if (!SpriteExists(sprite)) {
 		Debug(sprite, 1, "Tried to load non-existing sprite #{}. Probable cause: Wrong/missing NewGRFs", sprite);
@@ -1042,7 +1042,7 @@ void GfxClearSpriteCache()
 	/* Clear sprite ptr for all cached items */
 	for (uint i = 0; i != _spritecache_items; i++) {
 		SpriteCache *sc = GetSpriteCache(i);
-		if (sc->type != ST_RECOLOUR && sc->ptr != nullptr) DeleteEntryFromSpriteCache(i);
+		if (sc->type != SpriteType::Recolour && sc->ptr != nullptr) DeleteEntryFromSpriteCache(i);
 	}
 
 	VideoDriver::GetInstance()->ClearSystemSprites();