diff --git a/src/udp.c b/src/udp.c
index 3051382..d48f6fe 100644
--- a/src/udp.c
+++ b/src/udp.c
@@ -170,7 +170,7 @@ static int meth_sendto(lua_State *L) {
     case PF_INET6: {
         struct sockaddr_in6 addr;
         memset(&addr, 0, sizeof(addr));
-        if (!inet_pton(AF_INET6, ip, &addr.sin6_addr) != 1)
+        if (inet_pton(AF_INET6, ip, &addr.sin6_addr) != 1)
             luaL_argerror(L, 3, "invalid ip address");
         addr.sin6_family = AF_INET6;
         addr.sin6_port = htons(port);