diff --git a/src/hb-ot-cff-common.hh b/src/hb-ot-cff-common.hh
index b2843d394..1ac7611de 100644
--- a/src/hb-ot-cff-common.hh
+++ b/src/hb-ot-cff-common.hh
@@ -107,7 +107,7 @@ struct CFFIndex
 
     /* serialize CFFIndex header */
     if (unlikely (!c->extend_min (this))) return_trace (false);
-    this->count = it.len ();
+    this->count = hb_len (it);
     if (!this->count) return_trace (true);
     if (unlikely (!c->extend (this->offSize))) return_trace (false);
     this->offSize = off_size;