diff --git a/src/atsamd/main.c b/src/atsamd/main.c
index d3943e6a..37b6cc8b 100644
--- a/src/atsamd/main.c
+++ b/src/atsamd/main.c
@@ -5,9 +5,27 @@
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
 #include "board/armcm_boot.h" // armcm_main
+#include "board/misc.h" // bootloader_request
+#include "board/io.h" // writel
+#include "board/irq.h" // irq_disable
 #include "internal.h" // SystemInit
 #include "sched.h" // sched_main
 
+void
+bootloader_request(void)
+{
+    if (!CONFIG_FLASH_START)
+        return;
+    // Bootloader hack
+    irq_disable();
+#if CONFIG_MACH_SAMD21
+    writel((void*)0x20007FFC, 0x07738135);
+#elif CONFIG_MACH_SAMX5
+    writel((void*)(HSRAM_ADDR + HSRAM_SIZE - 4), 0xf01669ef);
+#endif
+    NVIC_SystemReset();
+}
+
 // Main entry point - called from armcm_boot.c:ResetHandler()
 void
 armcm_main(void)
diff --git a/src/atsamd/usbserial.c b/src/atsamd/usbserial.c
index bf3e0e80..938f8e21 100644
--- a/src/atsamd/usbserial.c
+++ b/src/atsamd/usbserial.c
@@ -7,9 +7,7 @@
 #include <string.h> // memcpy
 #include "autoconf.h" // CONFIG_FLASH_START
 #include "board/armcm_boot.h" // armcm_enable_irq
-#include "board/io.h" // readl
-#include "board/irq.h" // irq_disable
-#include "board/misc.h" // bootloader_request
+#include "board/io.h" // writeb
 #include "board/usb_cdc.h" // usb_notify_ep0
 #include "board/usb_cdc_ep.h" // USB_CDC_EP_BULK_IN
 #include "command.h" // DECL_CONSTANT_STR
@@ -172,21 +170,6 @@ usb_set_configure(void)
         USB_DEVICE_EPINTENSET_TRCPT0 | USB_DEVICE_EPINTENSET_TRCPT1);
 }
 
-void
-bootloader_request(void)
-{
-    if (!CONFIG_FLASH_START)
-        return;
-    // Bootloader hack
-    irq_disable();
-#if CONFIG_MACH_SAMD21
-    writel((void*)0x20007FFC, 0x07738135);
-#elif CONFIG_MACH_SAMX5
-    writel((void*)(HSRAM_ADDR + HSRAM_SIZE - 4), 0xf01669ef);
-#endif
-    NVIC_SystemReset();
-}
-
 
 /****************************************************************
  * Setup and interrupts