diff --git a/src/modems/hayes.c b/src/modems/hayes.c
index 531c99b..b2ff28f 100644
--- a/src/modems/hayes.c
+++ b/src/modems/hayes.c
@@ -4065,6 +4065,7 @@ static void _on_code_cusd(HayesChannel * channel, char const * answer)
 	/* FIXME really implement */
 	if(sscanf(answer, "%u\"%31[^\"]\",%u", &u, buf, &u) >= 2)
 	{
+		buf[sizeof(buf) - 1] = '\0';
 		event->notification.content = buf;
 		hayes->helper->event(hayes->helper->modem, event);
 	}