diff --git a/embassy-usb-hid/src/lib.rs b/embassy-usb-hid/src/lib.rs
index b9ba4f1e7..a75cb8c38 100644
--- a/embassy-usb-hid/src/lib.rs
+++ b/embassy-usb-hid/src/lib.rs
@@ -112,7 +112,8 @@ fn build<'d, D: Driver<'d>>(
     let len = config.report_descriptor.len();
 
     let mut func = builder.function(USB_CLASS_HID, USB_SUBCLASS_NONE, USB_PROTOCOL_NONE);
-    let mut iface = func.interface(Some(control));
+    let mut iface = func.interface();
+    iface.handler(control);
     let mut alt = iface.alt_setting(USB_CLASS_HID, USB_SUBCLASS_NONE, USB_PROTOCOL_NONE);
 
     // HID descriptor
@@ -438,7 +439,7 @@ impl<'d> ControlHandler for Control<'d> {
         self.out_report_offset.store(0, Ordering::Release);
     }
 
-    fn get_descriptor<'a>(&'a mut self, req: Request, buf: &'a mut [u8]) -> InResponse<'a> {
+    fn get_descriptor<'a>(&'a mut self, req: Request, _buf: &'a mut [u8]) -> InResponse<'a> {
         match (req.value >> 8) as u8 {
             HID_DESC_DESCTYPE_HID_REPORT => InResponse::Accepted(self.report_descriptor),
             HID_DESC_DESCTYPE_HID => InResponse::Accepted(&self.hid_descriptor),
diff --git a/embassy-usb-serial/src/lib.rs b/embassy-usb-serial/src/lib.rs
index 4bddc31af..4587bf713 100644
--- a/embassy-usb-serial/src/lib.rs
+++ b/embassy-usb-serial/src/lib.rs
@@ -178,7 +178,8 @@ impl<'d, D: Driver<'d>> CdcAcmClass<'d, D> {
         let mut func = builder.function(USB_CLASS_CDC, CDC_SUBCLASS_ACM, CDC_PROTOCOL_NONE);
 
         // Control interface
-        let mut iface = func.interface(Some(control));
+        let mut iface = func.interface();
+        iface.handler(control);
         let comm_if = iface.interface_number();
         let data_if = u8::from(comm_if) + 1;
         let mut alt = iface.alt_setting(USB_CLASS_CDC, CDC_SUBCLASS_ACM, CDC_PROTOCOL_NONE);
@@ -218,7 +219,7 @@ impl<'d, D: Driver<'d>> CdcAcmClass<'d, D> {
         let comm_ep = alt.endpoint_interrupt_in(8, 255);
 
         // Data interface
-        let mut iface = func.interface(None);
+        let mut iface = func.interface();
         let data_if = iface.interface_number();
         let mut alt = iface.alt_setting(USB_CLASS_CDC_DATA, 0x00, CDC_PROTOCOL_NONE);
         let read_ep = alt.endpoint_bulk_out(max_packet_size);
diff --git a/embassy-usb/src/builder.rs b/embassy-usb/src/builder.rs
index c0aea9838..07b6c79d1 100644
--- a/embassy-usb/src/builder.rs
+++ b/embassy-usb/src/builder.rs
@@ -267,17 +267,14 @@ impl<'a, 'd, D: Driver<'d>> FunctionBuilder<'a, 'd, D> {
     /// Add an interface to the function.
     ///
     /// Interface numbers are guaranteed to be allocated consecutively, starting from 0.
-    pub fn interface(
-        &mut self,
-        handler: Option<&'d mut dyn ControlHandler>,
-    ) -> InterfaceBuilder<'_, 'd, D> {
+    pub fn interface(&mut self) -> InterfaceBuilder<'_, 'd, D> {
         if let Some(i) = self.iface_count_index {
             self.builder.config_descriptor.buf[i] += 1;
         }
 
         let number = self.builder.interfaces.len() as _;
         let iface = Interface {
-            handler,
+            handler: None,
             current_alt_setting: 0,
             num_alt_settings: 0,
         };
@@ -307,6 +304,10 @@ impl<'a, 'd, D: Driver<'d>> InterfaceBuilder<'a, 'd, D> {
         self.interface_number
     }
 
+    pub fn handler(&mut self, handler: &'d mut dyn ControlHandler) {
+        self.builder.interfaces[self.interface_number.0 as usize].handler = Some(handler);
+    }
+
     /// Add an alternate setting to the interface and write its descriptor.
     ///
     /// Alternate setting numbers are guaranteed to be allocated consecutively, starting from 0.