diff --git a/src/hb-iter.hh b/src/hb-iter.hh
index e86e795d1..f8b0987d6 100644
--- a/src/hb-iter.hh
+++ b/src/hb-iter.hh
@@ -30,7 +30,6 @@
 #include "hb.hh"
 #include "hb-algs.hh" // for hb_addressof
 #include "hb-meta.hh"
-#include "hb-null.hh"
 
 
 /* Unified iterator object.
@@ -155,7 +154,7 @@ template<typename T, typename B>
 struct _hb_is_iterable
 { enum { value = false }; };
 template<typename T>
-struct _hb_is_iterable<T, hb_bool_tt<true || sizeof (Null(T).iter ())> >
+struct _hb_is_iterable<T, hb_bool_tt<true || sizeof (hb_declval (T).iter ())> >
 { enum { value = true }; };
 
 template<typename T>
diff --git a/src/hb.hh b/src/hb.hh
index 18b0e0bd2..37445c57c 100644
--- a/src/hb.hh
+++ b/src/hb.hh
@@ -635,7 +635,7 @@ _hb_memalign(void **memptr, size_t alignment, size_t size)
 #include "hb-atomic.hh"	// Requires: hb-meta
 #include "hb-null.hh"	// Requires: hb-meta
 #include "hb-algs.hh"	// Requires: hb-null
-#include "hb-iter.hh"	// Requires: hb-algs hb-meta hb-null
+#include "hb-iter.hh"	// Requires: hb-algs hb-meta
 #include "hb-debug.hh"	// Requires: hb-algs hb-atomic
 #include "hb-array.hh"	// Requires: hb-algs hb-iter hb-null
 #include "hb-vector.hh"	// Requires: hb-array hb-null