diff --git a/src/client/user_ifdhandler.c b/src/client/user_ifdhandler.c
index 5e7fb7a..c6a9392 100644
--- a/src/client/user_ifdhandler.c
+++ b/src/client/user_ifdhandler.c
@@ -396,7 +396,8 @@
 
 	INIT_LLIST_HEAD(&ct->it_msgq);
 	osmo_fd_setup(&ct->it_ofd, cfg->it_sock_fd, OSMO_FD_READ, &it_sock_fd_cb, ct, 0);
-	osmo_fd_register(&ct->it_ofd);
+	rc = osmo_fd_register(&ct->it_ofd);
+	OSMO_ASSERT(rc == 0);
 
 	/* ensure we get properly cleaned up if cancelled */
 	pthread_cleanup_push(client_pthread_cleanup, ct);