diff --git a/openbsc/src/nat/bsc_mgcp_utils.c b/openbsc/src/nat/bsc_mgcp_utils.c
index 7bba413..79bd2a5 100644
--- a/openbsc/src/nat/bsc_mgcp_utils.c
+++ b/openbsc/src/nat/bsc_mgcp_utils.c
@@ -113,7 +113,7 @@
 	int len;
 
 	len = snprintf(buf, sizeof(buf),
-		       "MDCX 23 %d@mgw MGCP 1.0\r\n"
+		       "MDCX 23 %x@mgw MGCP 1.0\r\n"
 		       "Z: noanswer\r\n"
 		       "\r\n"
 		       "c=IN IP4 %s\r\n"
@@ -133,7 +133,7 @@
 	int len;
 
 	len = snprintf(buf, sizeof(buf),
-		       "DLCX 23 %d@mgw MGCP 1.0\r\n"
+		       "DLCX 23 %x@mgw MGCP 1.0\r\n"
 		       "Z: noanswer\r\n", endpoint);
 	if (len < 0) {
 		LOGP(DMGCP, LOGL_ERROR, "snprintf for DLCX failed.\n");