diff --git a/ml_util.cpp b/ml_util.cpp
index 2d9924c..006daff 100644
--- a/ml_util.cpp
+++ b/ml_util.cpp
@@ -3,6 +3,7 @@
 
 #include <string>
 #include <vector>
+#include <filesystem>
 
 const std::vector<std::string> commands {
 	"eval", "type", "parse", "do", "if", "for", "while", "scope", "quote", "defn", 
@@ -17,12 +18,11 @@ const std::vector<std::string> commands {
 	};
 
 std::string get_history_file_dir() {
-	// TODO not portable and in function
-	std::string file{"/.ml_history.txt"};
+	std::string filename{".ml_history.txt"};
 	const char *t = std::getenv("HOME");
 
-	if (t == nullptr) return "/tmp/" + file;
-	else return std::string{t} + "/" + file;
+	if (t == nullptr) return std::filesystem::temp_directory_path() / filename;
+	else return std::filesystem::path(std::string{t}) /filename;
 }	
 
 MlEnvironment * repl_env = nullptr;
@@ -68,7 +68,7 @@ void completion(const char *buf, linenoiseCompletions *lc) {
         std::string token = str.substr(pos+1);
         std::string begining = str.substr(0, pos+1);
 
-        // TODO optimize not to get all lambdas, but those beginning with token
+        // PERF optimize not to get all lambdas, but those beginning with token
         std::vector<std::string> lambdas = repl_env->get_lambdas_list();
     	lambdas.insert(end(lambdas), begin(commands), end(commands));