diff --git a/src/keel/media.cpp b/src/keel/media.cpp
index 46a36d937..4af8cb0d6 100644
--- a/src/keel/media.cpp
+++ b/src/keel/media.cpp
@@ -178,9 +178,8 @@ ox::Error setRomFs(Context &ctx, ox::UPtr<ox::FileSystem> fs) noexcept {
 }
 
 ox::Result<ox::UniquePtr<ox::FileSystem>> loadRomFs(ox::CRStringView path) noexcept {
-	const auto lastDot = ox_lastIndexOf(path, '.');
-	const auto fsExt = lastDot != -1 ? substr(path, static_cast<std::size_t>(lastDot)) : "";
-	if (ox_strcmp(fsExt, ".oxfs") == 0) {
+	auto const lastDot = ox::lastIndexOf(path, '.');
+	if (!lastDot.error && substr(path, lastDot.value) == ".oxfs") {
 		oxRequire(rom, loadRom(path));
 		return {ox::make_unique<ox::FileSystem32>(rom, 32 * ox::units::MB, unloadRom)};
 	} else {