diff --git a/atusb/fw/ep0.c b/atusb/fw/ep0.c
index b41f85f..81c2a3f 100644
--- a/atusb/fw/ep0.c
+++ b/atusb/fw/ep0.c
@@ -209,5 +209,5 @@ static int my_setup(const struct setup_request *setup)
 
 void ep0_init(void)
 {
-	user_setups[0] = my_setup;
+	user_setup = my_setup;
 }
diff --git a/atusb/fw/usb/atu2.c b/atusb/fw/usb/atu2.c
index f626864..6ab9146 100644
--- a/atusb/fw/usb/atu2.c
+++ b/atusb/fw/usb/atu2.c
@@ -190,7 +190,6 @@ void usb_poll(void)
 	if (flags & (1 << EORSTI)) {
 		if (user_reset)
 			user_reset();
-		user_setup = NULL;
 		ep_init();
 		UDINT &= ~(1 << EORSTI);
 	}
diff --git a/atusb/fw/usb/dfu.c b/atusb/fw/usb/dfu.c
index a70c52b..0ba2b81 100644
--- a/atusb/fw/usb/dfu.c
+++ b/atusb/fw/usb/dfu.c
@@ -280,7 +280,7 @@ static void my_reset(void)
 
 void dfu_init(void)
 {
-	user_setups[0] = my_setup;
+	user_setup = my_setup;
 	user_get_descriptor = my_descr;
 	user_reset = my_reset;
 }
diff --git a/atusb/fw/usb/usb.c b/atusb/fw/usb/usb.c
index b127069..8239735 100644
--- a/atusb/fw/usb/usb.c
+++ b/atusb/fw/usb/usb.c
@@ -36,7 +36,7 @@ extern void panic(void);
 #endif
 
 int (*user_setup)(const struct setup_request *setup);
-int (*user_setups[2])(const struct setup_request *setup);
+void (*user_set_interface)(int nth);
 int (*user_get_descriptor)(uint8_t type, uint8_t index,
     const uint8_t **reply, uint8_t *size);
 void (*user_reset)(void);
@@ -145,7 +145,8 @@ int handle_setup(const struct setup_request *setup)
 			    p += p[0]) {
 				if (p[2] == setup->wIndex &&
 				    p[3] == setup->wValue) {
-					user_setup = user_setups[i];
+					if (user_set_interface)
+						user_set_interface(i);
 					return 1;
 				}
 				i++;
@@ -170,8 +171,6 @@ int handle_setup(const struct setup_request *setup)
 	default:
 		if (user_setup)
 			return user_setup(setup);
-		if (user_setups[0])
-			return user_setups[0](setup);
 		return 0;
 	}
 
diff --git a/atusb/fw/usb/usb.h b/atusb/fw/usb/usb.h
index 8808e06..8b7eebc 100644
--- a/atusb/fw/usb/usb.h
+++ b/atusb/fw/usb/usb.h
@@ -133,7 +133,7 @@ extern const uint8_t config_descriptor[];
 extern struct ep_descr eps[];
 
 extern int (*user_setup)(const struct setup_request *setup);
-extern int (*user_setups[2])(const struct setup_request *setup);
+extern void (*user_set_interface)(int nth);
 extern int (*user_get_descriptor)(uint8_t type, uint8_t index,
     const uint8_t **reply, uint8_t *size);
 extern void (*user_reset)(void);