diff --git a/examples/device/audio_4_channel_mic/src/usb_descriptors.c b/examples/device/audio_4_channel_mic/src/usb_descriptors.c
index 2b66bfe34..b6a5bd5c2 100644
--- a/examples/device/audio_4_channel_mic/src/usb_descriptors.c
+++ b/examples/device/audio_4_channel_mic/src/usb_descriptors.c
@@ -85,9 +85,11 @@ enum
   // LPC 17xx and 40xx endpoint type (bulk/interrupt/iso) are fixed by its number
   // 0 control, 1 In, 2 Bulk, 3 Iso, 4 In etc ...
   #define EPNUM_AUDIO   0x03
+
 #elif TU_CHECK_MCU(NRF5X)
   // nRF5x ISO can only be endpoint 8
   #define EPNUM_AUDIO   0x08
+
 #else
   #define EPNUM_AUDIO   0x01
 #endif
diff --git a/examples/device/audio_test/src/usb_descriptors.c b/examples/device/audio_test/src/usb_descriptors.c
index a4e9dc8e1..348f5eede 100644
--- a/examples/device/audio_test/src/usb_descriptors.c
+++ b/examples/device/audio_test/src/usb_descriptors.c
@@ -82,11 +82,16 @@ enum
 #define CONFIG_TOTAL_LEN    	(TUD_CONFIG_DESC_LEN + CFG_TUD_AUDIO * TUD_AUDIO_MIC_ONE_CH_DESC_LEN)
 
 #if CFG_TUSB_MCU == OPT_MCU_LPC175X_6X || CFG_TUSB_MCU == OPT_MCU_LPC177X_8X || CFG_TUSB_MCU == OPT_MCU_LPC40XX
-// LPC 17xx and 40xx endpoint type (bulk/interrupt/iso) are fixed by its number
-// 0 control, 1 In, 2 Bulk, 3 Iso, 4 In etc ...
-#define EPNUM_AUDIO   0x03
+  // LPC 17xx and 40xx endpoint type (bulk/interrupt/iso) are fixed by its number
+  // 0 control, 1 In, 2 Bulk, 3 Iso, 4 In etc ...
+  #define EPNUM_AUDIO   0x03
+
+#elif TU_CHECK_MCU(NRF5X)
+  // nRF5x ISO can only be endpoint 8
+  #define EPNUM_AUDIO   0x08
+
 #else
-#define EPNUM_AUDIO   0x01
+  #define EPNUM_AUDIO   0x01
 #endif
 
 uint8_t const desc_configuration[] =
diff --git a/examples/device/uac2_headset/src/usb_descriptors.c b/examples/device/uac2_headset/src/usb_descriptors.c
index 64fa3c25b..9e97845b8 100644
--- a/examples/device/uac2_headset/src/usb_descriptors.c
+++ b/examples/device/uac2_headset/src/usb_descriptors.c
@@ -77,22 +77,25 @@ uint8_t const * tud_descriptor_device_cb(void)
 #define CONFIG_TOTAL_LEN    	(TUD_CONFIG_DESC_LEN + CFG_TUD_AUDIO * TUD_AUDIO_HEADSET_STEREO_DESC_LEN)
 
 #if CFG_TUSB_MCU == OPT_MCU_LPC175X_6X || CFG_TUSB_MCU == OPT_MCU_LPC177X_8X || CFG_TUSB_MCU == OPT_MCU_LPC40XX
-// LPC 17xx and 40xx endpoint type (bulk/interrupt/iso) are fixed by its number
-// 0 control, 1 In, 2 Bulk, 3 Iso, 4 In etc ...
-#define EPNUM_AUDIO_IN    0x03
-#define EPNUM_AUDIO_OUT   0x03
+  // LPC 17xx and 40xx endpoint type (bulk/interrupt/iso) are fixed by its number
+  // 0 control, 1 In, 2 Bulk, 3 Iso, 4 In etc ...
+  #define EPNUM_AUDIO_IN    0x03
+  #define EPNUM_AUDIO_OUT   0x03
+
 #elif CFG_TUSB_MCU == OPT_MCU_NRF5X
-// ISO endpoints for NRF5x are fixed to 0x08 (0x88)
-#define EPNUM_AUDIO_IN    0x08
-#define EPNUM_AUDIO_OUT   0x08
+  // ISO endpoints for NRF5x are fixed to 0x08 (0x88)
+  #define EPNUM_AUDIO_IN    0x08
+  #define EPNUM_AUDIO_OUT   0x08
+
 #elif CFG_TUSB_MCU == OPT_MCU_SAMG  || CFG_TUSB_MCU ==  OPT_MCU_SAMX7X
-// SAMG & SAME70 don't support a same endpoint number with different direction IN and OUT
-//    e.g EP1 OUT & EP1 IN cannot exist together
-#define EPNUM_AUDIO_IN    0x01
-#define EPNUM_AUDIO_OUT   0x02
+  // SAMG & SAME70 don't support a same endpoint number with different direction IN and OUT
+  //    e.g EP1 OUT & EP1 IN cannot exist together
+  #define EPNUM_AUDIO_IN    0x01
+  #define EPNUM_AUDIO_OUT   0x02
+
 #else
-#define EPNUM_AUDIO_IN    0x01
-#define EPNUM_AUDIO_OUT   0x01
+  #define EPNUM_AUDIO_IN    0x01
+  #define EPNUM_AUDIO_OUT   0x01
 #endif
 
 uint8_t const desc_configuration[] =
diff --git a/src/class/vendor/vendor_device.c b/src/class/vendor/vendor_device.c
index c73ca2538..188b561d7 100644
--- a/src/class/vendor/vendor_device.c
+++ b/src/class/vendor/vendor_device.c
@@ -216,7 +216,7 @@ uint16_t vendord_open(uint8_t rhport, tusb_desc_interface_t const * desc_itf, ui
     if ( p_vendor->ep_in ) maybe_transmit(p_vendor);
   }
 
-  return (uint16_t) true;
+  return drv_len;
 }
 
 bool vendord_xfer_cb(uint8_t rhport, uint8_t ep_addr, xfer_result_t result, uint32_t xferred_bytes)