diff --git a/examples/device/webusb_serial/src/main.c b/examples/device/webusb_serial/src/main.c
index 50794bdba..155768b76 100644
--- a/examples/device/webusb_serial/src/main.c
+++ b/examples/device/webusb_serial/src/main.c
@@ -196,6 +196,7 @@ bool tud_vendor_control_xfer_cb(uint8_t rhport, uint8_t stage, tusb_control_requ
           tud_vendor_write_str("\r\nWebUSB interface connected\r\n");
           tud_vendor_write_flush();
         } else {
+          tud_vendor_write_clear(); // anything left in the buffer is now thrown out
           blink_interval_ms = BLINK_MOUNTED;
         }
 
diff --git a/src/class/vendor/vendor_device.c b/src/class/vendor/vendor_device.c
index 9972911e0..b8e6fec6f 100644
--- a/src/class/vendor/vendor_device.c
+++ b/src/class/vendor/vendor_device.c
@@ -160,6 +160,13 @@ uint32_t tud_vendor_n_write_available(uint8_t idx) {
   vendord_interface_t *p_itf = &_vendord_itf[idx];
   return tu_edpt_stream_write_available(&p_itf->stream.tx);
 }
+
+bool tud_vendor_n_write_clear(uint8_t idx) {
+  TU_VERIFY(idx < CFG_TUD_VENDOR, 0);
+  vendord_interface_t *p_itf = &_vendord_itf[idx];
+  tu_edpt_stream_clear(&p_itf->stream.tx);
+  return true;
+}
 #endif
 
 //--------------------------------------------------------------------+
diff --git a/src/class/vendor/vendor_device.h b/src/class/vendor/vendor_device.h
index d59c885d2..c3de4c49d 100644
--- a/src/class/vendor/vendor_device.h
+++ b/src/class/vendor/vendor_device.h
@@ -91,6 +91,9 @@ uint32_t tud_vendor_n_write_flush(uint8_t idx);
 
 // Return number of bytes available for writing in TX FIFO
 uint32_t tud_vendor_n_write_available(uint8_t idx);
+
+// Clear the transmit FIFO
+bool tud_vendor_n_write_clear(uint8_t idx);
 #endif
 
 // Write a null-terminated string to TX FIFO
@@ -148,6 +151,10 @@ TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_flush(void) {
 TU_ATTR_ALWAYS_INLINE static inline uint32_t tud_vendor_write_available(void) {
   return tud_vendor_n_write_available(0);
 }
+
+TU_ATTR_ALWAYS_INLINE static inline bool tud_vendor_write_clear(void) {
+  return tud_vendor_n_write_clear(0);
+}
 #endif
 
 // backward compatible