diff --git a/util.hpp b/util.hpp
index 05c400b..7e1aab6 100644
--- a/util.hpp
+++ b/util.hpp
@@ -98,6 +98,8 @@
  * @returns String representation of the ip.
  */
 std::string toString(const InAddrAny& addr);
+std::string toString(const struct in_addr& addr);
+std::string toString(const struct in6_addr& addr);
 
 /* @brief converts the prefix into subnetmask.
  * @param[in] addressFamily - IP address family(AF_INET/AF_INET6).