diff --git a/firmware/ice40-riscv/icE1usb/usb_desc_app.c b/firmware/ice40-riscv/icE1usb/usb_desc_app.c
index 153d70e..544ac23 100644
--- a/firmware/ice40-riscv/icE1usb/usb_desc_app.c
+++ b/firmware/ice40-riscv/icE1usb/usb_desc_app.c
@@ -6,6 +6,7 @@
  */
 
 #include <no2usb/usb_proto.h>
+#include <no2usb/usb_cdc_proto.h>
 #include <no2usb/usb_dfu_proto.h>
 #include <no2usb/usb.h>
 
@@ -13,6 +14,8 @@
 #define num_elem(a) (sizeof(a) / sizeof(a[0]))
 
 
+usb_cdc_union_desc_def(1);
+
 static const struct {
 	/* Configuration */
 	struct usb_conf_desc conf;
@@ -43,10 +46,9 @@
 #if 0
 	struct {
 		struct usb_intf_desc intf_ctl;
-		struct usb_cs_intf_hdr_desc cs_intf_hdr;
-		struct usb_cs_intf_acm_desc cs_intf_acm;
-		struct usb_cs_intf_union_desc cs_intf_union;
-		uint8_t cs_intf_union_slave;
+		struct usb_cdc_hdr_desc cdc_hdr;
+		struct usb_cdc_acm_desc cdc_acm;
+		struct usb_cdc_union_desc__1 cdc_union;
 		struct usb_ep_desc ep_ctl;
 		struct usb_intf_desc intf_data;
 		struct usb_ep_desc ep_data_out;
@@ -174,30 +176,30 @@
 			.bInterfaceNumber	= 1,
 			.bAlternateSetting	= 0,
 			.bNumEndpoints		= 1,
-			.bInterfaceClass	= 0x02,
-			.bInterfaceSubClass	= 0x02,
+			.bInterfaceClass	= USB_CLS_CDC_CONTROL,
+			.bInterfaceSubClass	= USB_CDC_SCLS_ACM,
 			.bInterfaceProtocol	= 0x00,
 			.iInterface		= 6,
 		},
-		.cs_intf_hdr = {
-			.bLength		= sizeof(struct usb_cs_intf_hdr_desc),
-			.bDescriptorType	= USB_DT_CS_INTF,
-			.bDescriptorsubtype	= 0x00,
+		.cdc_hdr = {
+			.bLength		= sizeof(struct usb_cdc_hdr_desc),
+			.bDescriptorType	= USB_CS_DT_INTF,
+			.bDescriptorsubtype	= USB_CDC_DST_HEADER,
 			.bcdCDC			= 0x0110,
 		},
-		.cs_intf_acm = {
-			.bLength		= sizeof(struct usb_cs_intf_acm_desc),
-			.bDescriptorType	= USB_DT_CS_INTF,
-			.bDescriptorsubtype	= 0x02,
+		.cdc_acm = {
+			.bLength		= sizeof(struct usb_cdc_acm_desc),
+			.bDescriptorType	= USB_CS_DT_INTF,
+			.bDescriptorsubtype	= USB_CDC_DST_ACM,
 			.bmCapabilities		= 0x02,
 		},
-		.cs_intf_union = {
-			.bLength		= sizeof(struct usb_cs_intf_union_desc) + 1,
-			.bDescriptorType	= USB_DT_CS_INTF,
-			.bDescriptorsubtype	= 0x06,
+		.cdc_union = {
+			.bLength		= sizeof(struct usb_cdc_union_desc) + 1,
+			.bDescriptorType	= USB_CS_DT_INTF,
+			.bDescriptorsubtype	= USB_CDC_DST_UNION,
 			.bMasterInterface	= 1,
+			.bSlaveInterface	= { 2 },
 		},
-		.cs_intf_union_slave = 2,
 		.ep_ctl = {
 			.bLength		= sizeof(struct usb_ep_desc),
 			.bDescriptorType	= USB_DT_EP,
@@ -212,7 +214,7 @@
 			.bInterfaceNumber	= 2,
 			.bAlternateSetting	= 0,
 			.bNumEndpoints		= 2,
-			.bInterfaceClass	= 0x0a,
+			.bInterfaceClass	= USB_CLS_CDC_DATA,
 			.bInterfaceSubClass	= 0x00,
 			.bInterfaceProtocol	= 0x00,
 			.iInterface		= 7,