diff -uNr wavemon-0.9.0/iw_scan.c wavemon-0.9.0.mod/iw_scan.c
--- wavemon-0.9.0/iw_scan.c	2018-12-30 03:08:25.000000000 +0200
+++ wavemon-0.9.0.mod/iw_scan.c	2019-07-03 19:33:39.729820897 +0300
@@ -368,6 +368,10 @@
 	sr->num.ch_stats = n < MAX_CH_STATS ? n : MAX_CH_STATS;
 }
 
+void on_exit_hook() {
+	if_set_down_on_exit(0, conf_ifname());
+}
+
 /** The actual scan thread. */
 void *do_scan(void *sr_ptr)
 {
@@ -430,8 +434,7 @@
 
 				if (if_set_up(conf_ifname()) < 0)
 					err_sys("Can not bring up interface '%s'", conf_ifname());
-				if (on_exit(if_set_down_on_exit, (void *)conf_ifname()) < 0)
-					snprintf(sr->msg, sizeof(sr->msg), "Warning: unable to restore %s down state on exit", conf_ifname());
+				atexit(on_exit_hook);
 				break;
 			}
 			/* fall through */