diff --git a/libs/main/containers/pimap.h b/libs/main/containers/pimap.h
index 01010f7c..17f9b713 100644
--- a/libs/main/containers/pimap.h
+++ b/libs/main/containers/pimap.h
@@ -610,7 +610,7 @@ public:
 		return ret;
 	}
 
-private:
+protected:
 	struct MapIndex {
 		MapIndex(const Key & k = Key(), size_t i = 0): key(k), index(i) {}
 		MapIndex(Key && k, size_t i = 0): key(std::move(k)), index(i) {}
@@ -627,6 +627,10 @@ private:
 	template<typename P, typename Key1, typename T1>
 	friend PIBinaryStream<P> & operator<<(PIBinaryStream<P> & s, const PIDeque<typename PIMap<Key1, T1>::MapIndex> & v);
 
+	PIVector<T> pim_content;
+	PIDeque<MapIndex> pim_index;
+
+private:
 	inline ssize_t _binarySearch(ssize_t first, ssize_t last, const Key & key, bool & found) const {
 		ssize_t mid = 0;
 		while (first <= last) {
@@ -678,10 +682,6 @@ private:
 	inline T & _value(ssize_t index) { return pim_content[pim_index[index].index]; }
 
 	inline const T & _value(ssize_t index) const { return pim_content[pim_index[index].index]; }
-
-
-	PIVector<T> pim_content;
-	PIDeque<MapIndex> pim_index;
 };
 
 
diff --git a/libs/main/containers/piset.h b/libs/main/containers/piset.h
index cf126b3d..6453703a 100644
--- a/libs/main/containers/piset.h
+++ b/libs/main/containers/piset.h
@@ -66,6 +66,90 @@ public:
 		_CSet::insert(v3, 0);
 	}
 
+
+	class const_iterator {
+		friend class PISet<T>;
+
+	private:
+		inline const_iterator(const PISet<T> * v, ssize_t p): parent(v), pos(p) {}
+		const PISet<T> * parent;
+		ssize_t pos;
+
+	public:
+		typedef T value_type;
+		typedef T * pointer;
+		typedef T & reference;
+		typedef std::ptrdiff_t difference_type;
+		typedef std::random_access_iterator_tag iterator_category;
+
+		inline const_iterator(): parent(0), pos(0) {}
+
+		inline const T & operator*() const { return parent->pim_index[pos].key; }
+		inline const T & operator->() const { return parent->pim_index[pos].key; }
+
+		inline const_iterator & operator++() {
+			++pos;
+			return *this;
+		}
+		inline const_iterator operator++(int) {
+			const auto tmp = *this;
+			++*this;
+			return tmp;
+		}
+		inline const_iterator & operator--() {
+			--pos;
+			return *this;
+		}
+		inline const_iterator operator--(int) {
+			const auto tmp = *this;
+			--*this;
+			return tmp;
+		}
+
+		inline const_iterator & operator+=(const const_iterator & it) {
+			pos += it.pos;
+			return *this;
+		}
+		inline const_iterator & operator+=(size_t p) {
+			pos += p;
+			return *this;
+		}
+		inline const_iterator & operator-=(const const_iterator & it) {
+			pos -= it.pos;
+			return *this;
+		}
+		inline const_iterator & operator-=(size_t p) {
+			pos -= p;
+			return *this;
+		}
+
+		friend inline const_iterator operator-(size_t p, const const_iterator & it) { return it - p; }
+		friend inline const_iterator operator-(const const_iterator & it, size_t p) {
+			auto tmp = it;
+			tmp -= p;
+			return tmp;
+		}
+		friend inline std::ptrdiff_t operator-(const const_iterator & it1, const const_iterator & it2) { return it1.pos - it2.pos; }
+
+		friend inline const_iterator operator+(size_t p, const const_iterator & it) { return it + p; }
+		friend inline const_iterator operator+(const const_iterator & it, size_t p) {
+			auto tmp = it;
+			tmp += p;
+			return tmp;
+		}
+
+		inline bool operator==(const const_iterator & it) const { return (pos == it.pos); }
+		inline bool operator!=(const const_iterator & it) const { return (pos != it.pos); }
+		friend inline bool operator<(const const_iterator & it1, const const_iterator & it2) { return it1.pos < it2.pos; }
+		friend inline bool operator<=(const const_iterator & it1, const const_iterator & it2) { return it1.pos <= it2.pos; }
+		friend inline bool operator>(const const_iterator & it1, const const_iterator & it2) { return it1.pos > it2.pos; }
+		friend inline bool operator>=(const const_iterator & it1, const const_iterator & it2) { return it1.pos >= it2.pos; }
+	};
+
+
+	inline const_iterator begin() const { return const_iterator(this, 0); }
+	inline const_iterator end() const { return const_iterator(this, _CSet::size()); }
+
 	//! Contructs set from vector of elements
 	explicit PISet(const PIVector<T> & values) {
 		if (values.isEmpty()) return;
@@ -199,10 +283,10 @@ inline PICout operator<<(PICout s, const PISet<Type> & v) {
 	s.saveAndSetControls(0);
 	s << "{";
 	bool first = true;
-	for (typename PIMap<Type, uchar>::const_iterator i = v.begin(); i != v.end(); ++i) {
+	for (const auto & i: v) {
 		if (!first) s << ", ";
 		first = false;
-		s << i.key();
+		s << i;
 	}
 	s << "}";
 	s.restoreControls();
diff --git a/utils/value_tree_translator/main.cpp b/utils/value_tree_translator/main.cpp
index ae2d6115..ce5747f1 100644
--- a/utils/value_tree_translator/main.cpp
+++ b/utils/value_tree_translator/main.cpp
@@ -285,10 +285,10 @@ int main(int argc, char * argv[]) {
 	ts << "<context>\n";
 	ts << "  <name>" << context << "</name>\n";
 	for (const auto & s: strings) {
-		TSMessage m = old.value(s.first);
-		m.filename  = locations.value(s.first.hash());
-		writeTSMessage(s.first, m);
-		old.remove(s.first);
+		TSMessage m = old.value(s);
+		m.filename  = locations.value(s.hash());
+		writeTSMessage(s, m);
+		old.remove(s);
 	}
 	if (!cli.hasArgument("no-obsolete")) {
 		for (const auto & i: old) {