diff --git a/cpu/esp32/stdio_usb_serial_jtag/usb_serial_jtag.c b/cpu/esp32/stdio_usb_serial_jtag/usb_serial_jtag.c
index cd9ec7d119..d167fb93e9 100644
--- a/cpu/esp32/stdio_usb_serial_jtag/usb_serial_jtag.c
+++ b/cpu/esp32/stdio_usb_serial_jtag/usb_serial_jtag.c
@@ -73,11 +73,11 @@ static void _serial_intr_handler(void *arg)
             }
             USB_SERIAL_JTAG.ep1.rdwr_byte = c;
         }
-        usb_serial_jtag_ll_txfifo_flush();
     }
 
     /* clear all interrupt flags */
-    usb_serial_jtag_ll_clr_intsts_mask(mask);
+    usb_serial_jtag_ll_clr_intsts_mask(USB_SERIAL_JTAG_LL_INTR_MASK);
+    usb_serial_jtag_ll_txfifo_flush();
 
     irq_isr_exit();
 }