diff --git a/ports/stm32/gccollect.c b/ports/stm32/gccollect.c
index 667bbc4327..083642bce3 100644
--- a/ports/stm32/gccollect.c
+++ b/ports/stm32/gccollect.c
@@ -24,23 +24,13 @@
  * THE SOFTWARE.
  */
 
-#include <stdio.h>
-#include <stdint.h>
-
-#include "py/mpstate.h"
 #include "py/gc.h"
 #include "py/mpthread.h"
 #include "shared/runtime/gchelper.h"
 #include "shared/runtime/softtimer.h"
 #include "gccollect.h"
-#include "systick.h"
 
 void gc_collect(void) {
-    // get current time, in case we want to time the GC
-    #if 0
-    uint32_t start = mp_hal_ticks_us();
-    #endif
-
     // start the GC
     gc_collect_start();
 
@@ -57,15 +47,4 @@ void gc_collect(void) {
 
     // end the GC
     gc_collect_end();
-
-    #if 0
-    // print GC info
-    uint32_t ticks = mp_hal_ticks_us() - start;
-    gc_info_t info;
-    gc_info(&info);
-    printf("GC@%lu %lums\n", start, ticks);
-    printf(" " UINT_FMT " total\n", info.total);
-    printf(" " UINT_FMT " : " UINT_FMT "\n", info.used, info.free);
-    printf(" 1=" UINT_FMT " 2=" UINT_FMT " m=" UINT_FMT "\n", info.num_1block, info.num_2block, info.max_block);
-    #endif
 }
diff --git a/ports/stm32/led.c b/ports/stm32/led.c
index fa211f1e14..e70c22532c 100644
--- a/ports/stm32/led.c
+++ b/ports/stm32/led.c
@@ -212,7 +212,6 @@ void led_state(pyb_led_t led, int state) {
     }
 
     const pin_obj_t *led_pin = pyb_led_obj[led - 1].led_pin;
-    // printf("led_state(%d,%d)\n", led, state);
     if (state == 0) {
         // turn LED off
         MICROPY_HW_LED_OFF(led_pin);
diff --git a/ports/stm32/rtc.c b/ports/stm32/rtc.c
index 874e427cff..92f64626a3 100644
--- a/ports/stm32/rtc.c
+++ b/ports/stm32/rtc.c
@@ -24,8 +24,6 @@
  * THE SOFTWARE.
  */
 
-#include <stdio.h>
-
 #include "py/runtime.h"
 #include "shared/timeutils/timeutils.h"
 #include "extint.h"
@@ -771,8 +769,6 @@ mp_obj_t pyb_rtc_wakeup(size_t n_args, const mp_obj_t *args) {
 
         NVIC_SetPriority(RTC_WKUP_IRQn, IRQ_PRI_RTC_WKUP);
         HAL_NVIC_EnableIRQ(RTC_WKUP_IRQn);
-
-        // printf("wut=%d wucksel=%d\n", wut, wucksel);
     } else {
         // clear WUTIE to disable interrupts
         RTC->CR &= ~RTC_CR_WUTIE;
@@ -833,7 +829,6 @@ mp_obj_t pyb_rtc_calibration(size_t n_args, const mp_obj_t *args) {
         HAL_RTCEx_SetSmoothCalib(&RTCHandle, RTC_SMOOTHCALIB_PERIOD_32SEC, cal_p, cal_m);
         return mp_const_none;
     } else {
-        // printf("CALR = 0x%x\n", (mp_uint_t) RTCHandle.Instance->CALR); // DEBUG
         // Test if CALP bit is set in CALR:
         if (RTCHandle.Instance->CALR & 0x8000) {
             cal = 512 - (RTCHandle.Instance->CALR & 0x1ff);
diff --git a/ports/stm32/storage.c b/ports/stm32/storage.c
index 848602a787..4623225804 100644
--- a/ports/stm32/storage.c
+++ b/ports/stm32/storage.c
@@ -24,9 +24,6 @@
  * THE SOFTWARE.
  */
 
-#include <stdint.h>
-#include <string.h>
-
 #include "py/runtime.h"
 #include "py/mperrno.h"
 #include "extmod/vfs_fat.h"
@@ -144,7 +141,6 @@ static void build_partition(uint8_t *buf, int boot, int type, uint32_t start_blo
 }
 
 bool storage_read_block(uint8_t *dest, uint32_t block) {
-    // printf("RD %u\n", block);
     if (block == 0) {
         // fake the MBR so we can decide on our own partition table
 
@@ -176,7 +172,6 @@ bool storage_read_block(uint8_t *dest, uint32_t block) {
 }
 
 bool storage_write_block(const uint8_t *src, uint32_t block) {
-    // printf("WR %u\n", block);
     if (block == 0) {
         // can't write MBR, but pretend we did
         return true;
diff --git a/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c b/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c
index 3708c75589..c32c20ab58 100644
--- a/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c
+++ b/ports/stm32/usbdev/class/src/usbd_cdc_msc_hid.c
@@ -821,23 +821,6 @@ static uint8_t USBD_CDC_MSC_HID_DeInit(USBD_HandleTypeDef *pdev, uint8_t cfgidx)
 }
 
 static uint8_t USBD_CDC_MSC_HID_Setup(USBD_HandleTypeDef *pdev, USBD_SetupReqTypedef *req) {
-
-    /*
-    printf("SU: %x %x %x %x\n", req->bmRequest, req->bRequest, req->wValue, req->wIndex);
-
-    This is what we get when MSC is IFACE=0 and CDC is IFACE=1,2:
-        SU: 21 22 0 1 -- USB_REQ_TYPE_CLASS | USB_REQ_RECIPIENT_INTERFACE; CDC_SET_CONTROL_LINE_STATE
-        SU: 21 20 0 1 -- USB_REQ_TYPE_CLASS | USB_REQ_RECIPIENT_INTERFACE; CDC_SET_LINE_CODING
-        SU: a1 fe 0 0 -- 0x80 | USB_REQ_TYPE_CLASS | USB_REQ_RECIPIENT_INTERFACE; BOT_GET_MAX_LUN; 0; 0
-        SU: 21 22 3 1 -- USB_REQ_TYPE_CLASS | USB_REQ_RECIPIENT_INTERFACE; CDC_SET_CONTROL_LINE_STATE
-
-    On a Mac OS X, with MSC then CDC:
-        SU: a1 fe 0 0
-        SU: 21 22 2 1
-        SU: 21 22 3 1
-        SU: 21 20 0 1
-    */
-
     usbd_cdc_msc_hid_state_t *usbd = pdev->pClassData;
 
     // Work out the recipient of the setup request
diff --git a/ports/stm32/usbdev/class/src/usbd_msc_scsi.c b/ports/stm32/usbdev/class/src/usbd_msc_scsi.c
index 2eb716ccde..78c8c5af19 100644
--- a/ports/stm32/usbdev/class/src/usbd_msc_scsi.c
+++ b/ports/stm32/usbdev/class/src/usbd_msc_scsi.c
@@ -123,12 +123,6 @@ int8_t SCSI_ProcessCmd(USBD_HandleTypeDef  *pdev,
                            uint8_t lun,
                            uint8_t *params)
 {
-    /*
-    if (params[0] != SCSI_READ10 && params[0] != SCSI_WRITE10) {
-        printf("SCSI_ProcessCmd(lun=%d, params=%x, %x)\n", lun, params[0], params[1]);
-    }
-    */
-
   switch (params[0])
   {
   case SCSI_TEST_UNIT_READY: