diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 21664fc..4241e6f 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -86,6 +86,7 @@
 	const void *dir_ops;	      /* Opaque; default directory operations */
 	int dir_per_block;	      /* dir entries per block */
 	int dir_per_block_bits;	      /* log2(dir_per_block) */
+	unsigned int vol_id;		/*volume ID*/
 
 	int fatent_shift;
 	struct fatent_operations *fatent_ops;