diff --git a/include/uapi/linux/hyperv.h b/include/uapi/linux/hyperv.h
index 78e4a86030dd2d295a1abba8ad6249668fdf7fef..0a8e6badb29bcf05f9a1c968a9c2e2c2d271df1e 100644
--- a/include/uapi/linux/hyperv.h
+++ b/include/uapi/linux/hyperv.h
@@ -137,7 +137,7 @@ struct hv_do_fcopy {
 	__u64	offset;
 	__u32	size;
 	__u8	data[DATA_FRAGMENT];
-};
+} __attribute__((packed));
 
 /*
  * An implementation of HyperV key value pair (KVP) functionality for Linux.