diff --git a/nx/external/bsd/include/netinet/in.h b/nx/external/bsd/include/netinet/in.h
index d9209cd276..a73d3b6bc9 100644
--- a/nx/external/bsd/include/netinet/in.h
+++ b/nx/external/bsd/include/netinet/in.h
@@ -684,6 +684,14 @@ struct sockaddr_in6 {
 	uint32_t        sin6_scope_id; /* Scope ID */
 };
 
+/*
+ * Argument structure for IPV6_JOIN_GROUP and IPV6_LEAVE_GROUP.
+ */
+struct ipv6_mreq {
+	struct in6_addr ipv6mr_multiaddr;
+	unsigned int    ipv6mr_interface;
+};
+
 extern const struct in6_addr in6addr_any;
 extern const struct in6_addr in6addr_loopback;