diff --git a/src/nostalgia/modules/core/src/tilesheet.cpp b/src/nostalgia/modules/core/src/tilesheet.cpp
index 18b62d04..fb336f79 100644
--- a/src/nostalgia/modules/core/src/tilesheet.cpp
+++ b/src/nostalgia/modules/core/src/tilesheet.cpp
@@ -52,7 +52,7 @@ TileSheet::SubSheet const *getSubsheet(TileSheet const&ts, SubSheetId const id)
 static ox::Optional<size_t> getPixelIdx(
 		TileSheet::SubSheet const&ss,
 		SubSheetId const id,
-		size_t idx,
+		size_t &idx,
 		int8_t const bpp) noexcept {
 	for (auto const&child: ss.subsheets) {
 		if (child.id == id) {
@@ -63,11 +63,12 @@ static ox::Optional<size_t> getPixelIdx(
 		}
 		idx += pixelCnt(child, bpp);
 	}
-	return {};
+	return ox::Optional<size_t>{};
 }
 
 size_t getTileIdx(TileSheet const&ts, SubSheetId const id) noexcept {
-	auto const out = getPixelIdx(ts.subsheet, id, 0, ts.bpp);
+	size_t idx{};
+	auto const out = getPixelIdx(ts.subsheet, id, idx, ts.bpp);
 	return out.or_value(0) / PixelsPerTile;
 }