diff --git a/ml.cpp b/ml.cpp
index 66e7cb2..e2b42fc 100644
--- a/ml.cpp
+++ b/ml.cpp
@@ -643,7 +643,7 @@ const char * MlError::what() const noexcept {
 void MlEnvironment::combine(MlEnvironment const &other) {
 	// Normally, I would use the `insert` method of the `map` class,
 	// but it doesn't overwrite previously declared values for keys.
-	std::map<std::string, MlValue>::const_iterator itr = other.defs.begin();
+	auto itr = other.defs.begin();
 	for (; itr != other.defs.end(); itr++) {
 		// Iterate through the keys and assign each value.
 		defs[itr->first] = itr->second;
@@ -651,7 +651,7 @@ void MlEnvironment::combine(MlEnvironment const &other) {
 }
 
 std::ostream &operator<<(std::ostream &os, MlEnvironment const &e) {
-	std::map<std::string, MlValue>::const_iterator itr = e.defs.begin();
+	auto itr = e.defs.begin();
 	os << "{ ";
 	for (; itr != e.defs.end(); itr++) {
 		os << '\'' << itr->first << "' : " << itr->second.debug() << ", ";
@@ -667,7 +667,7 @@ void MlEnvironment::set(const std::string &name, MlValue value) {
 void MlEnvironment::setX(const std::string &name, MlValue value) {
 	MlEnvironment *e = this;
 	while (e != nullptr) {
-		std::map<std::string, MlValue>::const_iterator itr = e->defs.find(name);
+		auto itr = e->defs.find(name);
 		if (itr != e->defs.end()) {
 			e->set(name, value);
 			return;
@@ -2063,7 +2063,7 @@ void load_std_lib(MlEnvironment &env) {
 
 // Does this environment, or its parent environment, have a variable?
 bool MlEnvironment::has(const std::string &name) const {
-	std::map<std::string, MlValue>::const_iterator itr = defs.find(name);
+	auto itr = defs.find(name);
 	if (itr != defs.end())
 		// If it was found
 		return true;
@@ -2212,7 +2212,7 @@ MlValue MlEnvironment::get(const std::string &name) const {
 	if (it !=  builtin_funcs.end())
 		return MlValue(name, it->second);
 
-	std::map<std::string, MlValue>::const_iterator itr = defs.find(name);
+	auto itr = defs.find(name);
 	if (itr != defs.end()) return itr->second;
 	else if (parent_scope != nullptr) {
 		itr = parent_scope->defs.find(name);