diff --git a/src/eap_peer/eap_tnc.c b/src/eap_peer/eap_tnc.c
index 177d432c1..6c95f72c1 100644
--- a/src/eap_peer/eap_tnc.c
+++ b/src/eap_peer/eap_tnc.c
@@ -73,12 +73,13 @@ static struct wpabuf * eap_tnc_build_frag_ack(u8 id, u8 code)
 {
 	struct wpabuf *msg;
 
-	msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, 0, code, id);
+	msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, 1, code, id);
 	if (msg == NULL) {
 		wpa_printf(MSG_ERROR, "EAP-TNC: Failed to allocate memory "
 			   "for fragment ack");
 		return NULL;
 	}
+	wpabuf_put_u8(msg, EAP_TNC_VERSION); /* Flags */
 
 	wpa_printf(MSG_DEBUG, "EAP-TNC: Send fragment ack");
 
diff --git a/src/eap_server/eap_tnc.c b/src/eap_server/eap_tnc.c
index 4eddf8b25..b4fd49523 100644
--- a/src/eap_server/eap_tnc.c
+++ b/src/eap_server/eap_tnc.c
@@ -173,12 +173,13 @@ static struct wpabuf * eap_tnc_build_frag_ack(u8 id, u8 code)
 {
 	struct wpabuf *msg;
 
-	msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, 0, code, id);
+	msg = eap_msg_alloc(EAP_VENDOR_IETF, EAP_TYPE_TNC, 1, code, id);
 	if (msg == NULL) {
 		wpa_printf(MSG_ERROR, "EAP-TNC: Failed to allocate memory "
 			   "for fragment ack");
 		return NULL;
 	}
+	wpabuf_put_u8(msg, EAP_TNC_VERSION); /* Flags */
 
 	wpa_printf(MSG_DEBUG, "EAP-TNC: Send fragment ack");