diff --git a/src/ip_utils.h b/src/ip_utils.h
index f8abd98cf60c63736ec82097a2fb9f96462971c9..f42c0c37470c0bea83d918a0fe760b1792bdbaf6 100644
--- a/src/ip_utils.h
+++ b/src/ip_utils.h
@@ -92,7 +92,7 @@ public:
     IpAddr(const pj_sockaddr& ip, socklen_t len)
         : addr()
     {
-        if (len > sizeof(addr))
+        if (len > static_cast<socklen_t>(sizeof(addr)))
             throw std::invalid_argument("IpAddr(): length overflows internal storage type");
         memcpy(&addr, &ip, len);
     }