diff --git a/src/n2n.c b/src/n2n.c
index 21c7973..c6a7ace 100644
--- a/src/n2n.c
+++ b/src/n2n.c
@@ -723,7 +723,7 @@ extern char * sock_to_cstr (n2n_sock_str_t out,
 
         tmp[0] = '\0';
         inet_ntop(AF_INET6, sock->addr.v6, tmp, sizeof(n2n_sock_str_t));
-        snprintf(out, N2N_SOCKBUF_SIZE, "%s:%hu", tmp[0] ? tmp : "", sock->port);
+        snprintf(out, N2N_SOCKBUF_SIZE, "[%s]:%hu", tmp[0] ? tmp : "", sock->port);
         return out;
     } else {
         const uint8_t * a = sock->addr.v4;