diff --git a/openair2/ENB_APP/enb_config.c b/openair2/ENB_APP/enb_config.c
index 17746637e9..d01ed1d3f3 100644
--- a/openair2/ENB_APP/enb_config.c
+++ b/openair2/ENB_APP/enb_config.c
@@ -2296,6 +2296,7 @@ int RCconfig_S1(MessageDef *msg_p, uint32_t i) {
 		S1AP_REGISTER_ENB_REQ (msg_p).mme_ip_address[l].ipv4 = 1;
 		S1AP_REGISTER_ENB_REQ (msg_p).mme_ip_address[l].ipv6 = 0;
 	      } else if (strcmp(*(S1ParamList.paramarray[l][ENB_MME_IP_ADDRESS_PREFERENCE_IDX].strptr), "ipv6") == 0) {
+                S1AP_REGISTER_ENB_REQ (msg_p).mme_ip_address[l].ipv4 = 0;
 		S1AP_REGISTER_ENB_REQ (msg_p).mme_ip_address[l].ipv6 = 1;
 	      } else if (strcmp(*(S1ParamList.paramarray[l][ENB_MME_IP_ADDRESS_PREFERENCE_IDX].strptr), "no") == 0) {
 		S1AP_REGISTER_ENB_REQ (msg_p).mme_ip_address[l].ipv4 = 1;