diff --git a/channels/chan_sip.c b/channels/chan_sip.c
index 0d0f4465828aaaadb939b81b05b46b7c986a1145..8c54f02ba3632385776bc00d28d14353be92ad29 100644
--- a/channels/chan_sip.c
+++ b/channels/chan_sip.c
@@ -13472,7 +13472,7 @@ static enum sip_result add_sdp(struct sip_request *resp, struct sip_pvt *p, int
 		}
 
 		if (max_audio_packet_size) {
-			ast_str_append(&a_text, 0, "a=maxptime:%d\r\n", max_audio_packet_size);
+			ast_str_append(&a_audio, 0, "a=maxptime:%d\r\n", max_audio_packet_size);
 		}
 
 		if (!doing_directmedia) {