1 files changed, 1 insertions, 0 deletions
diff --git a/tree.h b/tree.h
index f883b8c7..c545e280 100644
--- a/tree.h
+++ b/tree.h
@@ -26,6 +26,7 @@
  */
 
 extern val tree_s, tree_iter_s, tree_fun_whitelist_s;
+extern struct cobj_class *tree_cls, *tree_iter_cls;
 
 #define tree_fun_whitelist (deref(lookup_var_l(nil, tree_fun_whitelist_s)))