diff --git a/examples/bluetooth/ble_spp_client/main/spp_client_demo.c b/examples/bluetooth/ble_spp_client/main/spp_client_demo.c
index fe8485ef48..da8a596adf 100644
--- a/examples/bluetooth/ble_spp_client/main/spp_client_demo.c
+++ b/examples/bluetooth/ble_spp_client/main/spp_client_demo.c
@@ -494,7 +494,7 @@ void spp_heart_beat_task(void * arg)
                                               spp_conn_id,
                                               (db+SPP_IDX_SPP_HEARTBEAT_VAL)->attribute_handle,
                                               sizeof(heartbeat_s),
-                                              (char *)heartbeat_s,
+                                              (uint8_t *)heartbeat_s,
                                               ESP_GATT_WRITE_TYPE_RSP,
                                               ESP_GATT_AUTH_REQ_NONE);
                     vTaskDelay(5000 / portTICK_PERIOD_MS);