diff --git a/include/usb.h b/include/usb.h
new file mode 100644
index 0000000..9868dc1
--- /dev/null
+++ b/include/usb.h
@@ -0,0 +1,14 @@
+#ifndef __USB_H
+#define __USB_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void usb_isr(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
\ No newline at end of file
diff --git a/src/main.c b/src/main.c
index d525faa..1efeb01 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,17 +1,21 @@
 #include <stdio.h>
+#include <irq.h>
 #include <printf.h>
 #include <uart.h>
-#include <irq.h>
+#include <usb.h>
 
 #include <generated/csr.h>
 
 void isr(void) {
-	unsigned int irqs;
-	
-	irqs = irq_pending() & irq_getmask();
-	
-	if(irqs & (1 << UART_INTERRUPT))
-		uart_isr();
+    unsigned int irqs;
+    
+    irqs = irq_pending() & irq_getmask();
+    
+    if (irqs & (1 << USB_INTERRUPT))
+        usb_isr();
+
+    if (irqs & (1 << UART_INTERRUPT))
+        uart_isr();
 }
 
 static void rv_putchar(void *ignored, char c) {
@@ -21,8 +25,8 @@ static void rv_putchar(void *ignored, char c) {
 
 static void init(void) {
     irq_setmask(0);
-	irq_setie(1);
-	uart_init();
+    irq_setie(1);
+    uart_init();
     init_printf(NULL, rv_putchar);
 }
 
diff --git a/src/usb.c b/src/usb.c
new file mode 100644
index 0000000..911a546
--- /dev/null
+++ b/src/usb.c
@@ -0,0 +1,5 @@
+#include <usb.h>
+
+void usb_isr(void) {
+    return;
+}
\ No newline at end of file