diff --git a/cpp/src/main.cpp b/cpp/src/main.cpp
index 63eeacb..7dfbb5a 100644
--- a/cpp/src/main.cpp
+++ b/cpp/src/main.cpp
@@ -77,6 +77,14 @@ int main(int argc, char *argv[]) {
 
   CLI11_PARSE(app, argc, argv);
 
+  // Always ensure split_levels includes 0 (country-wide output file).
+  // User-provided --split-levels=1,2,3 means "also split into sub-regions",
+  // but the country-level file (boundary_ESP_1.json) must always be generated.
+  if (std::find(split_levels.begin(), split_levels.end(), 0) ==
+      split_levels.end()) {
+    split_levels.insert(split_levels.begin(), 0);
+  }
+
   // Set PROJ_DATA so PROJ can find proj.db next to the exe
   {
     auto exe_dir = fs::path(argv[0]).parent_path();
diff --git a/dist/win-x64/boundaries.exe b/dist/win-x64/boundaries.exe
index f5b68aa..f91b3ca 100644
Binary files a/dist/win-x64/boundaries.exe and b/dist/win-x64/boundaries.exe differ