diff --git a/sys/include/usb/usbus.h b/sys/include/usb/usbus.h
index 008a6ac7ad..090f969d9c 100644
--- a/sys/include/usb/usbus.h
+++ b/sys/include/usb/usbus.h
@@ -182,8 +182,21 @@ typedef enum {
  */
 typedef struct {
     /**
-     * @brief function pointer to retrieve the header content of this header
-     * generator
+     * @brief function pointer to format the descriptor content of this
+     * descriptor generator. The content of this descriptor is prefixes before
+     * the descriptor of the object it is part of.
+     *
+     * @param usbus The usbus context
+     * @param arg   Additional argument for the header generator
+     *
+     * @return      Length of the generated descriptor
+     */
+    size_t (*fmt_pre_descriptor)(usbus_t *usbus, void *arg);
+
+    /**
+     * @brief function pointer to format the descriptor content of this
+     * descriptor generator. The content of this descriptor is appended after
+     * the descriptor of the object it is part of.
      *
      * @param usbus The usbus context
      * @param arg   Additional argument for the header generator
@@ -195,8 +208,10 @@ typedef struct {
         /**
          * @brief USBUS generic header generator generated length
          *
-         * Must return the length of the header that will be generated by
-         * @ref get_header
+         * Must return the total length of the descriptors that will be
+         * generated by @ref fmt_pre_descriptor and @ref get_header
+         * This function is used when @ref len_type is set to
+         * @ref USBUS_HDR_LEN_FUNC.
          *
          * @param usbus The usbus context
          * @param arg   Additional argument for the header generator
@@ -204,7 +219,14 @@ typedef struct {
          * @return      Length of the generated header
          */
         size_t (*get_header_len)(usbus_t *usbus, void *arg);
-        size_t fixed_len;           /**< length of the header if it is a fixed length */
+        /**
+         * @brief Fixed total length of the generated descriptors
+         *
+         * Must return the total length of the descriptors that will be
+         * generated by the @ref fmt_pre_descriptor and @ref get_header.
+         * This value is used when @ref len_type is set to @ref USBUS_HDR_LEN_FIXED.
+         */
+        size_t fixed_len;
     } len;                          /**< Fixed or generated length of the header */
     usbus_hdr_len_type_t len_type;  /**< Either USBUS_HDR_LEN_FIXED or USBUS_HDR_LEN_FUNC */
 } usbus_hdr_gen_funcs_t;
diff --git a/sys/usb/usbus/usbus_fmt.c b/sys/usb/usbus/usbus_fmt.c
index fe9738b119..8cc5b212f5 100644
--- a/sys/usb/usbus/usbus_fmt.c
+++ b/sys/usb/usbus/usbus_fmt.c
@@ -130,9 +130,28 @@ static size_t _hdrs_config_size(usbus_t *usbus)
     return len;
 }
 
-static inline size_t call_get_header(usbus_t *usbus, usbus_hdr_gen_t *hdr)
+static inline size_t _get_pre_header(usbus_t *usbus, usbus_hdr_gen_t *hdr)
 {
-    return hdr->funcs->get_header(usbus, hdr->arg);
+    return (hdr->funcs->fmt_pre_descriptor != NULL)
+        ? hdr->funcs->fmt_pre_descriptor(usbus, hdr->arg)
+        : 0;
+}
+
+static inline size_t _get_additional_header(usbus_t *usbus, usbus_hdr_gen_t *hdr)
+{
+    return (hdr->funcs->get_header != NULL)
+        ? hdr->funcs->get_header(usbus, hdr->arg)
+        : 0;
+}
+
+static size_t _hdrs_fmt_pre(usbus_t *usbus, usbus_hdr_gen_t *hdr)
+{
+    size_t len = 0;
+
+    for (; hdr; hdr = hdr->next) {
+        len += _get_pre_header(usbus, hdr);
+    }
+    return len;
 }
 
 static size_t _hdrs_fmt_additional(usbus_t *usbus, usbus_hdr_gen_t *hdr)
@@ -140,7 +159,7 @@ static size_t _hdrs_fmt_additional(usbus_t *usbus, usbus_hdr_gen_t *hdr)
     size_t len = 0;
 
     for (; hdr; hdr = hdr->next) {
-        len += call_get_header(usbus, hdr);
+        len += _get_additional_header(usbus, hdr);
     }
     return len;
 }
@@ -155,6 +174,7 @@ static size_t _hdrs_fmt_endpoints(usbus_t *usbus, usbus_endpoint_t *ep)
     size_t len = 0;
 
     while (ep) {
+        _hdrs_fmt_pre(usbus, ep->hdr_gen);
         usb_descriptor_endpoint_t usb_ep;
         memset(&usb_ep, 0, sizeof(usb_descriptor_endpoint_t));
         usb_ep.length = sizeof(usb_descriptor_endpoint_t);
@@ -215,6 +235,7 @@ static size_t _hdrs_fmt_ifaces(usbus_t *usbus)
     for (usbus_interface_t *iface = usbus->iface;
          iface;
          iface = iface->next) {
+        len += _hdrs_fmt_pre(usbus, iface->hdr_gen);
         usb_descriptor_interface_t usb_iface;
         _hdrs_fmt_iface(iface, &usb_iface);
         usb_iface.num_endpoints = _num_endpoints(iface);