diff --git a/core/federated/RTI/rti_remote.c b/core/federated/RTI/rti_remote.c
index ef7b3d519..4efe438e6 100644
--- a/core/federated/RTI/rti_remote.c
+++ b/core/federated/RTI/rti_remote.c
@@ -1198,6 +1198,9 @@ static int32_t receive_and_check_fed_id_message(int* socket_id, struct sockaddr_
       // If the connection is a peer-to-peer connection between two
       // federates, reject the connection with the WRONG_SERVER error.
       send_reject(socket_id, WRONG_SERVER);
+    } else if (buffer[0] == MSG_TYPE_FED_NONCE) {
+      send_reject(socket_id, RTI_NOT_EXECUTED_WITH_AUTH);
+      lf_print_error("RTI not executed with HMAC authentication option using -a or --auth.");
     } else {
       send_reject(socket_id, UNEXPECTED_MESSAGE);
     }
diff --git a/core/federated/federate.c b/core/federated/federate.c
index 498687d07..ad1ec1741 100644
--- a/core/federated/federate.c
+++ b/core/federated/federate.c
@@ -862,6 +862,9 @@ static int perform_hmac_authentication() {
     if (received[0] == MSG_TYPE_FAILED) {
       lf_print_error("RTI has failed.");
       return -1;
+    } else if (received[0] == MSG_TYPE_REJECT && received[1] == RTI_NOT_EXECUTED_WITH_AUTH) {
+      lf_print_error("RTI is not executed with HMAC option.");
+      return -1;
     } else {
       lf_print_error("Received unexpected response %u from the RTI (see net_common.h).", received[0]);
       return -1;
diff --git a/include/core/federated/network/net_common.h b/include/core/federated/network/net_common.h
index 202592aa8..accd075bc 100644
--- a/include/core/federated/network/net_common.h
+++ b/include/core/federated/network/net_common.h
@@ -696,4 +696,7 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 /** HMAC authentication failed. */
 #define HMAC_DOES_NOT_MATCH 6
 
+/** RTI not executed using -a or --auth option. */
+#define RTI_NOT_EXECUTED_WITH_AUTH 7
+
 #endif /* NET_COMMON_H */