diff --git a/src/class/cdc/cdc_host.c b/src/class/cdc/cdc_host.c
index 595e7fd62..5e45e8f6b 100644
--- a/src/class/cdc/cdc_host.c
+++ b/src/class/cdc/cdc_host.c
@@ -86,7 +86,7 @@ bool tuh_cdc_serial_is_mounted(uint8_t dev_addr)
 {
   // TODO consider all AT Command as serial candidate
   return tuh_cdc_mounted(dev_addr)                                         &&
-      (CDC_COMM_PROTOCOL_ATCOMMAND <= cdch_data[dev_addr-1].itf_protocol) &&
+      (CDC_COMM_PROTOCOL_NONE <= cdch_data[dev_addr-1].itf_protocol) &&
       (cdch_data[dev_addr-1].itf_protocol <= CDC_COMM_PROTOCOL_ATCOMMAND_CDMA);
 }
 
diff --git a/src/device/usbd.h b/src/device/usbd.h
index 7b04ef9a7..acefb6943 100644
--- a/src/device/usbd.h
+++ b/src/device/usbd.h
@@ -183,9 +183,9 @@ TU_ATTR_WEAK bool tud_vendor_control_complete_cb(uint8_t rhport, tusb_control_re
 // Interface number, string index, EP notification address and size, EP data address (out, in) and size.
 #define TUD_CDC_DESCRIPTOR(_itfnum, _stridx, _ep_notif, _ep_notif_size, _epout, _epin, _epsize) \
   /* Interface Associate */\
-  8, TUSB_DESC_INTERFACE_ASSOCIATION, _itfnum, 2, TUSB_CLASS_CDC, CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL, CDC_COMM_PROTOCOL_ATCOMMAND, 0,\
+  8, TUSB_DESC_INTERFACE_ASSOCIATION, _itfnum, 2, TUSB_CLASS_CDC, CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL, CDC_COMM_PROTOCOL_NONE, 0,\
   /* CDC Control Interface */\
-  9, TUSB_DESC_INTERFACE, _itfnum, 0, 1, TUSB_CLASS_CDC, CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL, CDC_COMM_PROTOCOL_ATCOMMAND, _stridx,\
+  9, TUSB_DESC_INTERFACE, _itfnum, 0, 1, TUSB_CLASS_CDC, CDC_COMM_SUBCLASS_ABSTRACT_CONTROL_MODEL, CDC_COMM_PROTOCOL_NONE, _stridx,\
   /* CDC Header */\
   5, TUSB_DESC_CS_INTERFACE, CDC_FUNC_DESC_HEADER, U16_TO_U8S_LE(0x0120),\
   /* CDC Call */\