diff --git a/src/platforms/native/platform.c b/src/platforms/native/platform.c
index 338cd857..1804e175 100644
--- a/src/platforms/native/platform.c
+++ b/src/platforms/native/platform.c
@@ -304,57 +304,3 @@ static void setup_vbus_irq(void)
 
 	exti15_10_isr();
 }
-
-#ifdef ENABLE_DEBUG
-enum {
-	RDI_SYS_OPEN = 0x01,
-	RDI_SYS_WRITE = 0x05,
-	RDI_SYS_ISTTY = 0x09,
-};
-
-int rdi_write(int fn, const char *buf, size_t len)
-{
-	(void)fn;
-	if (debug_bmp)
-		return len - usbuart_debug_write(buf, len);
-
-	return 0;
-}
-
-struct ex_frame {
-	union {
-		int syscall;
-		int retval;
-	};
-	const int *params;
-	uint32_t r2, r3, r12, lr, pc;
-};
-
-void debug_monitor_handler_c(struct ex_frame *sp)
-{
-	/* Return to after breakpoint instruction */
-	sp->pc += 2;
-
-	switch (sp->syscall) {
-	case RDI_SYS_OPEN:
-		sp->retval = 1;
-		break;
-	case RDI_SYS_WRITE:
-		sp->retval = rdi_write(sp->params[0], (void*)sp->params[1], sp->params[2]);
-		break;
-	case RDI_SYS_ISTTY:
-		sp->retval = 1;
-		break;
-	default:
-		sp->retval = -1;
-	}
-
-}
-
-asm(".globl debug_monitor_handler\n"
-    ".thumb_func\n"
-    "debug_monitor_handler: \n"
-    "    mov r0, sp\n"
-    "    b debug_monitor_handler_c\n");
-
-#endif
diff --git a/src/platforms/stm32/usbuart.c b/src/platforms/stm32/usbuart.c
index ed74d36c..a4a772e1 100644
--- a/src/platforms/stm32/usbuart.c
+++ b/src/platforms/stm32/usbuart.c
@@ -250,3 +250,57 @@ void USBUSART_TIM_ISR(void)
 	/* process FIFO */
 	usbuart_run();
 }
+
+#ifdef ENABLE_DEBUG
+enum {
+	RDI_SYS_OPEN = 0x01,
+	RDI_SYS_WRITE = 0x05,
+	RDI_SYS_ISTTY = 0x09,
+};
+
+int rdi_write(int fn, const char *buf, size_t len)
+{
+	(void)fn;
+	if (debug_bmp)
+		return len - usbuart_debug_write(buf, len);
+
+	return 0;
+}
+
+struct ex_frame {
+	union {
+		int syscall;
+		int retval;
+	};
+	const int *params;
+	uint32_t r2, r3, r12, lr, pc;
+};
+
+void debug_monitor_handler_c(struct ex_frame *sp)
+{
+	/* Return to after breakpoint instruction */
+	sp->pc += 2;
+
+	switch (sp->syscall) {
+	case RDI_SYS_OPEN:
+		sp->retval = 1;
+		break;
+	case RDI_SYS_WRITE:
+		sp->retval = rdi_write(sp->params[0], (void*)sp->params[1], sp->params[2]);
+		break;
+	case RDI_SYS_ISTTY:
+		sp->retval = 1;
+		break;
+	default:
+		sp->retval = -1;
+	}
+
+}
+
+asm(".globl debug_monitor_handler\n"
+    ".thumb_func\n"
+    "debug_monitor_handler: \n"
+    "    mov r0, sp\n"
+    "    b debug_monitor_handler_c\n");
+
+#endif