diff --git a/firmware/usbstack/usb_charging_only.c b/firmware/usbstack/usb_charging_only.c
index e20d1885a0..145d0f684c 100644
--- a/firmware/usbstack/usb_charging_only.c
+++ b/firmware/usbstack/usb_charging_only.c
@@ -24,6 +24,7 @@
 #include "usb_drv.h"
 #include "kernel.h"
 #include "usb_charging_only.h"
+#include "usb_class_driver.h"
 
 //#define LOGF_ENABLE
 #include "logf.h"
@@ -66,9 +67,7 @@ int usb_charging_only_get_config_descriptor(unsigned char *dest,int max_packet_s
     unsigned char *orig_dest = dest;
 
     interface_descriptor.bInterfaceNumber=usb_interface;
-    memcpy(dest,&interface_descriptor,sizeof(struct usb_interface_descriptor));
-
-    dest+=sizeof(struct usb_interface_descriptor);
+    PACK_DESCRIPTOR(dest, interface_descriptor);
 
     return (dest-orig_dest);
 }
diff --git a/firmware/usbstack/usb_class_driver.h b/firmware/usbstack/usb_class_driver.h
index 22b1c6888c..b51eb3e93f 100644
--- a/firmware/usbstack/usb_class_driver.h
+++ b/firmware/usbstack/usb_class_driver.h
@@ -85,4 +85,10 @@ struct usb_class_driver {
 #endif
 };
 
+#define PACK_DESCRIPTOR(dest, descriptor) \
+    do { \
+        memcpy(dest, &(descriptor), sizeof(descriptor)); \
+        dest += sizeof(descriptor); \
+    } while (0)
+
 #endif
diff --git a/firmware/usbstack/usb_serial.c b/firmware/usbstack/usb_serial.c
index b7d5062237..514df0dc2b 100644
--- a/firmware/usbstack/usb_serial.c
+++ b/firmware/usbstack/usb_serial.c
@@ -24,7 +24,7 @@
 #include "usb_drv.h"
 #include "kernel.h"
 #include "usb_serial.h"
-
+#include "usb_class_driver.h"
 //#define LOGF_ENABLE
 #include "logf.h"
 
@@ -102,19 +102,16 @@ int usb_serial_get_config_descriptor(unsigned char *dest,int max_packet_size)
 {
     unsigned char *orig_dest = dest;
 
-    endpoint_descriptor.wMaxPacketSize=max_packet_size;
-    interface_descriptor.bInterfaceNumber=usb_interface;
+    interface_descriptor.bInterfaceNumber = usb_interface;
+    PACK_DESCRIPTOR(dest, interface_descriptor);
 
-    memcpy(dest,&interface_descriptor,sizeof(struct usb_interface_descriptor));
-    dest+=sizeof(struct usb_interface_descriptor);
+    endpoint_descriptor.wMaxPacketSize = max_packet_size;
 
     endpoint_descriptor.bEndpointAddress = ep_in;
-    memcpy(dest,&endpoint_descriptor,sizeof(struct usb_endpoint_descriptor));
-    dest+=sizeof(struct usb_endpoint_descriptor);
+    PACK_DESCRIPTOR(dest, endpoint_descriptor);
 
     endpoint_descriptor.bEndpointAddress = ep_out;
-    memcpy(dest,&endpoint_descriptor,sizeof(struct usb_endpoint_descriptor));
-    dest+=sizeof(struct usb_endpoint_descriptor);
+    PACK_DESCRIPTOR(dest, endpoint_descriptor);
 
     return (dest - orig_dest);
 }
diff --git a/firmware/usbstack/usb_storage.c b/firmware/usbstack/usb_storage.c
index eb1db5d884..2a3808dd92 100644
--- a/firmware/usbstack/usb_storage.c
+++ b/firmware/usbstack/usb_storage.c
@@ -22,6 +22,7 @@
 #include "system.h"
 #include "usb_core.h"
 #include "usb_drv.h"
+#include "usb_class_driver.h"
 //#define LOGF_ENABLE
 #include "logf.h"
 #include "storage.h"
@@ -371,24 +372,20 @@ int usb_storage_set_first_interface(int interface)
 
 int usb_storage_get_config_descriptor(unsigned char *dest,int max_packet_size)
 {
-    endpoint_descriptor.wMaxPacketSize=max_packet_size;
-    interface_descriptor.bInterfaceNumber=usb_interface;
+    unsigned char *orig_dest = dest;
 
-    memcpy(dest,&interface_descriptor,
-           sizeof(struct usb_interface_descriptor));
-    dest+=sizeof(struct usb_interface_descriptor);
+    interface_descriptor.bInterfaceNumber = usb_interface;
+    PACK_DESCRIPTOR(dest, interface_descriptor);
+
+    endpoint_descriptor.wMaxPacketSize = max_packet_size;
 
     endpoint_descriptor.bEndpointAddress = ep_in;
-    memcpy(dest,&endpoint_descriptor,
-           sizeof(struct usb_endpoint_descriptor));
-    dest+=sizeof(struct usb_endpoint_descriptor);
+    PACK_DESCRIPTOR(dest, endpoint_descriptor);
 
     endpoint_descriptor.bEndpointAddress = ep_out;
-    memcpy(dest,&endpoint_descriptor,
-           sizeof(struct usb_endpoint_descriptor));
+    PACK_DESCRIPTOR(dest, endpoint_descriptor);
 
-    return sizeof(struct usb_interface_descriptor) + 
-           2*sizeof(struct usb_endpoint_descriptor);
+    return (dest - orig_dest);
 }
 
 void usb_storage_init_connection(void)