Index: channels/chan_mgcp.c
===================================================================
--- channels/chan_mgcp.c	(revision 89681)
+++ channels/chan_mgcp.c	(working copy)
@@ -2623,7 +2623,7 @@
 		while (strlen(p->dtmf_buf) == len){
 			ast_safe_sleep(chan, loop_pause);
 			timeout -= loop_pause;
-			if ( (timeout -= loop_pause) <= 0){
+			if ( (timeout = loop_pause) <= 0){
 				res = 0;
 				break;
 			}