diff --git a/mqtt_client.c b/mqtt_client.c
index 9c1599a..ae1746d 100644
--- a/mqtt_client.c
+++ b/mqtt_client.c
@@ -129,6 +129,7 @@ static esp_err_t esp_mqtt_set_config(esp_mqtt_client_handle_t client, const esp_
         client->connect_info.will_message = malloc(config->lwt_msg_len);
         mem_assert(client->connect_info.will_message);
         memcpy(client->connect_info.will_message, config->lwt_msg, config->lwt_msg_len);
+        client->connect_info.will_length = config->lwt_msg_len;
     } else if (config->lwt_msg[0]) {
         client->connect_info.will_message = strdup(config->lwt_msg);
         client->connect_info.will_length = strlen(config->lwt_msg);