diff --git a/tests/test/host/hid/test_hidh_keyboard.c b/tests/test/host/hid/test_hidh_keyboard.c
index b437c9cab..12f3d7e4b 100644
--- a/tests/test/host/hid/test_hidh_keyboard.c
+++ b/tests/test/host/hid/test_hidh_keyboard.c
@@ -119,9 +119,11 @@ void test_keyboard_open_ok(void)
   TEST_ASSERT_EQUAL(TUSB_ERROR_NONE, hidh_keyboard_open_subtask(dev_addr, (uint8_t*) p_kbd_interface_desc, &length));
 
   tusbh_device_get_state_IgnoreAndReturn(TUSB_DEVICE_STATE_CONFIGURED);
-  TEST_ASSERT_EQUAL(2, tusbh_hid_keyboard_no_instances(dev_addr)); // init instance to 1
+  TEST_ASSERT_EQUAL(2, tusbh_hid_keyboard_no_instances(dev_addr)); // init set instance number to 1
   TEST_ASSERT_PIPE_HANDLE(pipe_hdl, p_hidh_kbd_interface->pipe_in);
   TEST_ASSERT_EQUAL(8, p_hidh_kbd_interface->report_size);
+  TEST_ASSERT_EQUAL(sizeof(tusb_descriptor_interface_t) + sizeof(tusb_hid_descriptor_hid_t) + sizeof(tusb_descriptor_endpoint_t),
+                   length);
 }
 
 void test_keyboard_init(void)
diff --git a/tinyusb/class/hid_host_keyboard.c b/tinyusb/class/hid_host_keyboard.c
index 2647f9bca..43031d6eb 100644
--- a/tinyusb/class/hid_host_keyboard.c
+++ b/tinyusb/class/hid_host_keyboard.c
@@ -101,17 +101,24 @@ void hidh_keyboard_init(void)
 
 tusb_error_t hidh_keyboard_open_subtask(uint8_t dev_addr, uint8_t const *descriptor, uint16_t *p_length)
 {
-  descriptor += *descriptor; // skip interface
-  descriptor += *descriptor; // TODO skip HID, only support std keyboard
+  uint8_t *p_desc = descriptor;
+
+  p_desc += p_desc[DESCRIPTOR_OFFSET_LENGTH]; // skip interface
+  p_desc += p_desc[DESCRIPTOR_OFFSET_LENGTH]; // TODO skip HID, only support std keyboard
+
+  // set ASAP, in case of error, p_length has to be not zero to prevent infinite re-open
+  (*p_length) = p_desc - descriptor;
 
   keyboard_interface_t *p_kbd = get_kbd_instance(dev_addr, keyboard_data[dev_addr-1].instance_count);
 
-  ASSERT_INT(TUSB_DESC_ENDPOINT, descriptor[DESCRIPTOR_OFFSET_TYPE], TUSB_ERROR_INVALID_PARA);
+  ASSERT_INT(TUSB_DESC_ENDPOINT, p_desc[DESCRIPTOR_OFFSET_TYPE], TUSB_ERROR_INVALID_PARA);
 
-  p_kbd->pipe_in = hcd_pipe_open(dev_addr, (tusb_descriptor_endpoint_t*) descriptor, TUSB_CLASS_HID);
+  p_kbd->pipe_in = hcd_pipe_open(dev_addr, (tusb_descriptor_endpoint_t*) p_desc, TUSB_CLASS_HID);
+
+  p_desc += p_desc[DESCRIPTOR_OFFSET_LENGTH]; // advance endpoint descriptor
+  (*p_length) = p_desc - descriptor;
 
   ASSERT (pipehandle_is_valid(p_kbd->pipe_in), TUSB_ERROR_HCD_FAILED);
-
   keyboard_data[dev_addr-1].instance_count++;
 
   return TUSB_ERROR_NONE;