--- a/src/core/filesystem.cc	Mon Nov 10 15:51:45 2025 -0500
+++ b/src/core/filesystem.cc	Mon Jan 19 20:50:40 2026 -0500
@@ -5,6 +5,7 @@
 #include <QStandardPaths>
 
 #include <filesystem>
+#include <unordered_map>
 
 #ifdef WIN32
 # include <windows.h>
@@ -100,7 +101,7 @@
 resort to old-fashioned recursion.  --paper
 */
 static void IterateDirectory(const std::filesystem::path &path, bool recursive,
-                             std::function<void(const std::filesystem::path &path)> func)
+                             const std::function<void(const std::filesystem::path &path)> &func)
 {
 	std::error_code ec;
 	static const std::filesystem::directory_iterator end;
@@ -180,7 +181,7 @@
 	}
 
 	/* unordered hashmap, path[found] */
-	std::unordered_map<std::filesystem::path, bool> paths_;
+	PathMap<bool> paths_;
 	bool recursive_;
 };