diff --git a/openbsc/src/libmgcp/mgcp_transcode.c b/openbsc/src/libmgcp/mgcp_transcode.c
index daf2510..12cce26 100644
--- a/openbsc/src/libmgcp/mgcp_transcode.c
+++ b/openbsc/src/libmgcp/mgcp_transcode.c
@@ -141,7 +141,6 @@
 {
 	struct mgcp_process_rtp_state *state;
 	enum audio_format src_fmt, dst_fmt;
-	const struct mgcp_rtp_codec *src_codec = &src_end->codec;
 	const struct mgcp_rtp_codec *dst_codec = &dst_end->codec;
 
 	/* cleanup first */
@@ -153,6 +152,8 @@
 	if (!src_end)
 		return 0;
 
+	const struct mgcp_rtp_codec *src_codec = &src_end->codec;
+
 	if (endp->tcfg->no_audio_transcoding) {
 		LOGP(DMGCP, LOGL_NOTICE,
 			"Transcoding disabled on endpoint 0x%x\n",