diff --git a/libc/net/lib_gethostbyaddr.c b/libc/net/lib_gethostbyaddr.c
index 6460e718bc6..8ef37a91512 100644
--- a/libc/net/lib_gethostbyaddr.c
+++ b/libc/net/lib_gethostbyaddr.c
@@ -82,6 +82,8 @@ FAR struct hostent *gethostbyaddr(FAR const void *addr, socklen_t len, int type)
   int ret;
 
   DEBUGASSERT(addr != NULL);
+  DEBUGASSERT(type == AF_INET || type == AF_INET6);
+
   ret = gethostbyaddr_r(addr, len, type, &g_hostent, g_hostbuffer,
                         CONFIG_NETDB_BUFSIZE, &h_errno);
   return ret == 0 ? &g_hostent : NULL;