diff --git a/channels/chan_zap.c b/channels/chan_zap.c
index e15ebe3a93..8db13660fb 100755
--- a/channels/chan_zap.c
+++ b/channels/chan_zap.c
@@ -3677,6 +3677,7 @@ static void *ss_thread(void *data)
 			else 
 				ast_dsp_digitmode(p->dsp,DSP_DIGITMODE_DTMF | p->dtmfrelax);
 		}
+		dtmfbuf[0] = 0;
 		/* Wait for the first digit only if immediate=no */
 		if (((p->sig == SIG_EM) || (p->sig == SIG_EMWINK)) && !p->immediate)
 			/* Wait for the first digit (up to 5 seconds). */