diff --git a/c_gen/templates/of_object.h b/c_gen/templates/of_object.h
index fee95e1..a85e33e 100644
--- a/c_gen/templates/of_object.h
+++ b/c_gen/templates/of_object.h
@@ -192,6 +192,8 @@
 
 int of_object_can_grow(of_object_t *obj, int new_len);
 
+void of_object_parent_length_update(of_object_t *obj, int delta);
+
 struct of_object_s {
     /* The control block for the underlying data buffer */
     of_wire_object_t wire_object;