diff --git a/res/res_pjsip_sdp_rtp.c b/res/res_pjsip_sdp_rtp.c
index a2dda373fb0da46f21a3bfceb74cb015ebae447c..96aad281b8d55aa1e8b03a6fb1a840bbcc4e1f42 100644
--- a/res/res_pjsip_sdp_rtp.c
+++ b/res/res_pjsip_sdp_rtp.c
@@ -274,6 +274,7 @@ static pjmedia_sdp_attr* generate_rtpmap_attr(pjmedia_sdp_media *media, pj_pool_
 	rtpmap.clock_rate = ast_rtp_lookup_sample_rate2(asterisk_format, format, code);
 	pj_strdup2(pool, &rtpmap.enc_name, ast_rtp_lookup_mime_subtype2(asterisk_format, format, code, 0));
 	rtpmap.param.slen = 0;
+	rtpmap.param.ptr = NULL;
 
 	pjmedia_sdp_rtpmap_to_attr(pool, &rtpmap, &attr);