diff --git a/src/spritecache.cpp b/src/spritecache.cpp
--- a/src/spritecache.cpp
+++ b/src/spritecache.cpp
@@ -810,7 +810,7 @@ static void *HandleInvalidSpriteRequest(
  */
 void *GetRawSprite(SpriteID sprite, SpriteType type, AllocatorProc *allocator)
 {
-	assert(IsMapgenSpriteID(sprite) == (type == ST_MAPGEN));
+	assert(type != ST_MAPGEN || IsMapgenSpriteID(sprite));
 	assert(type < ST_INVALID);
 
 	if (!SpriteExists(sprite)) {