Index: uspace/lib/drv/generic/remote_clock_dev.c
===================================================================
--- uspace/lib/drv/generic/remote_clock_dev.c	(revision ac310404db41765a81048fa21177f6268343d8a6)
+++ uspace/lib/drv/generic/remote_clock_dev.c	(revision 3ccba143f0e65b2bc3d74365b212d9d8c55bc2a8)
@@ -126,5 +126,5 @@
 	if (!clock_dev_ops->time_set) {
 		/* The driver does not support the time_set() functionality */
-		async_data_write_finalize(cid, NULL, 0);
+		async_answer_0(cid, ENOTSUP);
 		async_answer_0(callid, ENOTSUP);
 		return;