diff --git a/libs/main/containers/pivector.h b/libs/main/containers/pivector.h
index 8a626551..76ffbe3c 100644
--- a/libs/main/containers/pivector.h
+++ b/libs/main/containers/pivector.h
@@ -191,6 +191,18 @@ public:
 		return true;
 	}
 	inline bool operator !=(const PIVector<T> & t) const {return !(*this == t);}
+	inline bool operator <(const PIVector<T> & t) const {
+		if (piv_size != t.piv_size) return piv_size < t.piv_size;
+		for (size_t i = 0; i < piv_size; ++i)
+			if ((*this)[i] != t[i]) return (*this)[i] < t[i];
+		return false;
+	}
+	inline bool operator >(const PIVector<T> & t) const {
+		if (piv_size != t.piv_size) return piv_size > t.piv_size;
+		for (size_t i = 0; i < piv_size; ++i)
+			if ((*this)[i] != t[i]) return (*this)[i] > t[i];
+		return false;
+	}
 	inline bool contains(const T & v) const {
 		for (size_t i = 0; i < piv_size; ++i)
 			if (v == piv_data[i])