diff --git a/fs/btrfs/ulist.c b/fs/btrfs/ulist.c
index 13af1e41f9d7..33606025513d 100644
--- a/fs/btrfs/ulist.c
+++ b/fs/btrfs/ulist.c
@@ -266,7 +266,7 @@ int ulist_del(struct ulist *ulist, u64 val, u64 aux)
  * It is allowed to call ulist_add during an enumeration. Newly added items
  * are guaranteed to show up in the running enumeration.
  */
-struct ulist_node *ulist_next(struct ulist *ulist, struct ulist_iterator *uiter)
+struct ulist_node *ulist_next(const struct ulist *ulist, struct ulist_iterator *uiter)
 {
 	struct ulist_node *node;
 
diff --git a/fs/btrfs/ulist.h b/fs/btrfs/ulist.h
index 02fda0a2d4ce..b2cef187ea8e 100644
--- a/fs/btrfs/ulist.h
+++ b/fs/btrfs/ulist.h
@@ -66,7 +66,7 @@ static inline int ulist_add_merge_ptr(struct ulist *ulist, u64 val, void *aux,
 #endif
 }
 
-struct ulist_node *ulist_next(struct ulist *ulist,
+struct ulist_node *ulist_next(const struct ulist *ulist,
 			      struct ulist_iterator *uiter);
 
 #define ULIST_ITER_INIT(uiter) ((uiter)->cur_list = NULL)