diff --git a/ports/stm32/machine_uart.c b/ports/stm32/machine_uart.c
index bf7bcfb9cd..1bb1d2a1a7 100644
--- a/ports/stm32/machine_uart.c
+++ b/ports/stm32/machine_uart.c
@@ -523,6 +523,12 @@ STATIC mp_obj_t pyb_uart_irq(size_t n_args, const mp_obj_t *pos_args, mp_map_t *
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_KW(pyb_uart_irq_obj, 1, pyb_uart_irq);
 
+// Since uart.write() waits up to the last byte, uart.txdone() always returns True.
+STATIC mp_obj_t machine_uart_txdone(mp_obj_t self_in) {
+    return mp_const_true;
+}
+STATIC MP_DEFINE_CONST_FUN_OBJ_1(machine_uart_txdone_obj, machine_uart_txdone);
+
 STATIC const mp_rom_map_elem_t pyb_uart_locals_dict_table[] = {
     // instance methods
 
@@ -538,11 +544,13 @@ STATIC const mp_rom_map_elem_t pyb_uart_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_readinto), MP_ROM_PTR(&mp_stream_readinto_obj) },
     /// \method write(buf)
     { MP_ROM_QSTR(MP_QSTR_write), MP_ROM_PTR(&mp_stream_write_obj) },
+    { MP_ROM_QSTR(MP_QSTR_flush), MP_ROM_PTR(&mp_stream_flush_obj) },
     { MP_ROM_QSTR(MP_QSTR_irq), MP_ROM_PTR(&pyb_uart_irq_obj) },
 
     { MP_ROM_QSTR(MP_QSTR_writechar), MP_ROM_PTR(&pyb_uart_writechar_obj) },
     { MP_ROM_QSTR(MP_QSTR_readchar), MP_ROM_PTR(&pyb_uart_readchar_obj) },
     { MP_ROM_QSTR(MP_QSTR_sendbreak), MP_ROM_PTR(&pyb_uart_sendbreak_obj) },
+    { MP_ROM_QSTR(MP_QSTR_txdone), MP_ROM_PTR(&machine_uart_txdone_obj) },
 
     // class constants
     { MP_ROM_QSTR(MP_QSTR_RTS), MP_ROM_INT(UART_HWCONTROL_RTS) },
@@ -635,6 +643,9 @@ STATIC mp_uint_t pyb_uart_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_t a
         if ((flags & MP_STREAM_POLL_WR) && uart_tx_avail(self)) {
             ret |= MP_STREAM_POLL_WR;
         }
+    } else if (request == MP_STREAM_FLUSH) {
+        // Since uart.write() waits up to the last byte, uart.flush() always succeds.
+        ret = 0;
     } else {
         *errcode = MP_EINVAL;
         ret = MP_STREAM_ERROR;