diff --git a/channels/chan_dahdi.c b/channels/chan_dahdi.c
index e12b52d865..4f80e5a628 100644
--- a/channels/chan_dahdi.c
+++ b/channels/chan_dahdi.c
@@ -7994,7 +7994,7 @@ static void *do_monitor(void *data)
 								pthread_attr_t attr;
 								pthread_t threadid;
 								struct mwi_thread_data *mtd;
-								res2 = ioctl(last->subs[SUB_REAL].dfd, DAHDI_VMWI, res);
+								res2 = ioctl(last->subs[SUB_REAL].dfd, DAHDI_VMWI, &res);
 								if (res2) {
 									/* TODO: This message will ALWAYS be generated on some cards; any way to restrict it to those cards where it is interesting? */
 									ast_debug(3, "Unable to control message waiting led on channel %d: %s\n", last->channel, strerror(errno));