diff --git a/fs/libfs.c b/fs/libfs.c
index 09e1016..dcaf972 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -489,7 +489,8 @@
  * unique inode values later for this filesystem, then you must take care
  * to pass it an appropriate max_reserved value to avoid collisions.
  */
-int simple_fill_super(struct super_block *s, int magic, struct tree_descr *files)
+int simple_fill_super(struct super_block *s, unsigned long magic,
+		      struct tree_descr *files)
 {
 	struct inode *inode;
 	struct dentry *root;