diff --git a/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp b/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp
index 1eaa080c..cf7998c7 100644
--- a/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp
+++ b/src/nostalgia/modules/core/include/nostalgia/core/tilesheet.hpp
@@ -238,7 +238,7 @@ ox::Error resizeSubsheet(TileSheet::SubSheet &ss, int8_t pBpp, ox::Size const&sz
  * @return a valid version of idx
  */
 [[nodiscard]]
-TileSheet::SubSheetIdx validateSubSheetIdx(TileSheet const&ts, TileSheet::SubSheetIdx const&idx) noexcept;
+TileSheet::SubSheetIdx validateSubSheetIdx(TileSheet const&ts, TileSheet::SubSheetIdx idx) noexcept;
 
 [[nodiscard]]
 TileSheet::SubSheet const&getSubSheet(
diff --git a/src/nostalgia/modules/core/src/tilesheet.cpp b/src/nostalgia/modules/core/src/tilesheet.cpp
index 9f622ad4..18b62d04 100644
--- a/src/nostalgia/modules/core/src/tilesheet.cpp
+++ b/src/nostalgia/modules/core/src/tilesheet.cpp
@@ -191,27 +191,28 @@ ox::Result<ox::StringView> getNameFor(TileSheet::SubSheet const&ss, SubSheetId p
 
 
 TileSheet::SubSheetIdx validateSubSheetIdx(
-		TileSheet::SubSheetIdx const&pIdx,
+		TileSheet::SubSheetIdx &&pIdx,
 		std::size_t pIdxIt,
 		TileSheet::SubSheet const&pSubsheet) noexcept {
-	if (pIdxIt == pIdx.size()) {
-		return pIdx;
+	if (pIdxIt >= pIdx.size()) {
+		return std::move(pIdx);
 	}
-	const auto currentIdx = pIdx[pIdxIt];
+	auto &currentIdx = pIdx[pIdxIt];
 	if (pSubsheet.subsheets.size() <= currentIdx) {
-		auto out = pIdx;
-		if (!pSubsheet.subsheets.empty()) {
-			*out.back().value = pSubsheet.subsheets.size() - 1;
+		if (pSubsheet.subsheets.empty()) {
+			// currentIdx could not be repaired, remove
+			// this and all succeeding idxs and return
+			pIdx.resize(pIdxIt);
+			return std::move(pIdx);
 		} else {
-			out.pop_back();
+			currentIdx = pSubsheet.subsheets.size() - 1;
 		}
-		return out;
 	}
-	return validateSubSheetIdx(pIdx, pIdxIt + 1, pSubsheet.subsheets[pIdx[pIdxIt]]);
+	return validateSubSheetIdx(std::move(pIdx), pIdxIt + 1, pSubsheet.subsheets[currentIdx]);
 }
 
-TileSheet::SubSheetIdx validateSubSheetIdx(TileSheet const&ts, TileSheet::SubSheetIdx const&idx) noexcept {
-	return validateSubSheetIdx(idx, 0, ts.subsheet);
+TileSheet::SubSheetIdx validateSubSheetIdx(TileSheet const&ts, TileSheet::SubSheetIdx idx) noexcept {
+	return validateSubSheetIdx(std::move(idx), 0, ts.subsheet);
 }
 
 const TileSheet::SubSheet &getSubSheet(