--- libusb/usb.h
+++ libusb/usb.h
@@ -94,14 +94,14 @@
 struct usb_descriptor_header {
 	uint8_t  bLength;
 	uint8_t  bDescriptorType;
-};
+} __attribute__ ((packed));
 
 /* String descriptor */
 struct usb_string_descriptor {
 	uint8_t  bLength;
 	uint8_t  bDescriptorType;
 	uint16_t wData[1];
-};
+} __attribute__ ((packed));
 
 /* HID descriptor */
 struct usb_hid_descriptor {
@@ -113,7 +113,7 @@
 	/* uint8_t  bReportDescriptorType; */
 	/* uint16_t wDescriptorLength; */
 	/* ... */
-};
+} __attribute__ ((packed));
 
 /* Endpoint descriptor */
 #define USB_MAXENDPOINTS	32
@@ -200,7 +200,7 @@
 	uint8_t  iProduct;
 	uint8_t  iSerialNumber;
 	uint8_t  bNumConfigurations;
-};
+} __attribute__ ((packed));
 
 struct usb_ctrl_setup {
 	uint8_t  bRequestType;
@@ -208,7 +208,7 @@
 	uint16_t wValue;
 	uint16_t wIndex;
 	uint16_t wLength;
-};
+} __attribute__ ((packed));
 
 /*
  * Standard requests