diff --git a/channels/chan_zap.c b/channels/chan_zap.c
index 2f3cfd47a24a5dfc5149850d9c2cca437e310699..d05a19e80809accc7110afda8dfc0c077d1fe3b2 100755
--- a/channels/chan_zap.c
+++ b/channels/chan_zap.c
@@ -3843,8 +3843,8 @@ static void *ss_thread(void *data)
 {
 	struct ast_channel *chan = data;
 	struct zt_pvt *p = chan->pvt->pvt;
-	char exten[AST_MAX_EXTENSION];
-	char exten2[AST_MAX_EXTENSION];
+	char exten[AST_MAX_EXTENSION]="";
+	char exten2[AST_MAX_EXTENSION]="";
 	unsigned char buf[256];
 	char cid[256];
 	char dtmfbuf[300];