diff --git a/.vscode/settings.json b/.vscode/settings.json
index bca914e0..bb14f73d 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -102,7 +102,10 @@
         "ranges": "cpp",
         "span": "cpp",
         "gsl": "cpp",
-        "pointers": "cpp"
+        "pointers": "cpp",
+        "stacktrace": "cpp",
+        "assert": "cpp",
+        "narrow": "cpp"
     },
     "files.trimFinalNewlines": true,
     "files.insertFinalNewline": true,
diff --git a/src/fovtool/main.cpp b/src/fovtool/main.cpp
index 5a101150..446f84ba 100644
--- a/src/fovtool/main.cpp
+++ b/src/fovtool/main.cpp
@@ -43,11 +43,11 @@ static auto load_map(const std::filesystem::path& path) {
   auto map = MapInfo{
       .data = {map_width, map_height},
   };
-  for (int y = 0; y < lines.size(); ++y) {
+  for (int y = 0; y < gsl::narrow<int>(lines.size()); ++y) {
     const auto& line = lines.at(y);
     for (int x = 0; x < map_width; ++x) {
       static constexpr auto DEFAULT_CH = '.';
-      const auto ch = (gsl::narrow<size_t>(x) < line.size() ? line.at(x) : DEFAULT_CH);
+      const auto ch = (x < gsl::narrow<int>(line.size()) ? line.at(x) : DEFAULT_CH);
       const bool transparent = ch != '#';
       map.data.setProperties(x, y, transparent, false);
       if (ch == '@') {
@@ -59,7 +59,7 @@ static auto load_map(const std::filesystem::path& path) {
 }
 
 static auto render_map(const MapInfo& map) {
-  auto stream = std::basic_ostringstream<char32_t>{};
+  auto stream = std::ostringstream{};
   for (int y = 0; y < map.data.getHeight(); ++y) {
     if (y) stream << '\n';
     for (int x = 0; x < map.data.getWidth(); ++x) {
@@ -72,7 +72,7 @@ static auto render_map(const MapInfo& map) {
       stream << (visible ? (transparent ? '.' : '#') : (transparent ? ' ' : ' '));
     }
   }
-  return utf8::utf32to8(stream.rdbuf()->view());
+  return stream.rdbuf()->str();
 }
 
 int main(int argc, char** argv) {