diff --git a/include/lwmqtt.h b/include/lwmqtt.h
index 544dfd5..6fe8be7 100644
--- a/include/lwmqtt.h
+++ b/include/lwmqtt.h
@@ -132,8 +132,8 @@ struct lwmqtt_client_t {
   size_t write_buf_size, read_buf_size;
   uint8_t *write_buf, *read_buf;
 
-  void *callback_ref;
   lwmqtt_callback_t callback;
+  void *callback_ref;
 
   void *network;
   lwmqtt_network_read_t network_read;
diff --git a/src/client.c b/src/client.c
index 0013a6d..b07eff7 100644
--- a/src/client.c
+++ b/src/client.c
@@ -10,7 +10,9 @@ void lwmqtt_init(lwmqtt_client_t *client, uint8_t *write_buf, size_t write_buf_s
   client->write_buf_size = write_buf_size;
   client->read_buf = read_buf;
   client->read_buf_size = read_buf_size;
+
   client->callback = NULL;
+  client->callback_ref = NULL;
 
   client->network = NULL;
   client->network_read = NULL;