diff --git a/src/hb-array.hh b/src/hb-array.hh
index 9037179bc..6e458ffd8 100644
--- a/src/hb-array.hh
+++ b/src/hb-array.hh
@@ -251,7 +251,8 @@ struct hb_array_t : hb_iter_with_fallback_t<hb_array_t<Type>, Type&>
     if (end < start + 2)
       return;
 
-    for (unsigned lhs = start, rhs = end - 1; lhs < rhs; lhs++, rhs--)
+    unsigned stop = start + (end - start) / 2;
+    for (unsigned lhs = start, rhs = end - 1; lhs < stop; lhs++, rhs--)
       hb_swap (arrayZ[rhs], arrayZ[lhs]);
   }