diff --git a/src/hb-iter.hh b/src/hb-iter.hh
index b8d2dd5c3..42ae0749b 100644
--- a/src/hb-iter.hh
+++ b/src/hb-iter.hh
@@ -175,6 +175,14 @@ struct
 
 }
 HB_FUNCOBJ (hb_iter);
+struct
+{
+  template <typename T> unsigned
+  operator () (T&& c) const
+  { return c.len (); }
+
+}
+HB_FUNCOBJ (hb_len);
 
 /* Mixin to fill in what the subclass doesn't provide. */
 template <typename iter_t, typename item_t = typename iter_t::__item_t__>
diff --git a/src/test-iter.cc b/src/test-iter.cc
index 7ce6d8fde..10db97586 100644
--- a/src/test-iter.cc
+++ b/src/test-iter.cc
@@ -272,7 +272,7 @@ main (int argc, char **argv)
   hb_repeat (7u);
   hb_repeat (nullptr);
   hb_repeat (vl);
-  assert ((hb_range (10) | hb_take (3)).len () == 3);
+  assert (hb_len (hb_range (10) | hb_take (3)) == 3);
   assert (hb_range (9).len () == 9);
   assert (hb_range (2, 9).len () == 7);
   assert (hb_range (2, 9, 3).len () == 3);