diff --git a/buse.c b/buse.c
index c842de1..508fea3 100644
--- a/buse.c
+++ b/buse.c
@@ -88,9 +88,11 @@ int buse_main(const char* dev_file, const struct buse_operations *aop, void *use
     if(ioctl(nbd, NBD_SET_SOCK, sk) == -1){
       fprintf(stderr, "ioctl(nbd, NBD_SET_SOCK, sk) failed.[%s]\n", strerror(errno));
     }
+#if defined NBD_SET_FLAGS && defined NBD_FLAG_SEND_TRIM
     else if(ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) == -1){
       fprintf(stderr, "ioctl(nbd, NBD_SET_FLAGS, NBD_FLAG_SEND_TRIM) failed.[%s]\n", strerror(errno));
     }
+#endif
     else{
       err = ioctl(nbd, NBD_DO_IT);
       fprintf(stderr, "nbd device terminated with code %d\n", err);
@@ -153,14 +155,18 @@ int buse_main(const char* dev_file, const struct buse_operations *aop, void *use
       /* Handle a disconnect request. */
       aop->disc(userdata);
       return 0;
+#if defined NBD_CMD_FLUSH
     case NBD_CMD_FLUSH:
       reply.error = aop->flush(userdata);
       write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
       break;
+#endif
+#if defined NBD_CMD_TRIM
     case NBD_CMD_TRIM:
       reply.error = aop->trim(from, len, userdata);
       write_all(sk, (char*)&reply, sizeof(struct nbd_reply));
       break;
+#endif
     default:
       assert(0);
     }