diff --git a/src/hb-set.hh b/src/hb-set.hh
index 7d1c941e4..ff2a170d2 100644
--- a/src/hb-set.hh
+++ b/src/hb-set.hh
@@ -35,6 +35,8 @@
 template <typename impl_t>
 struct hb_sparseset_t
 {
+  static constexpr bool realloc_move = true;
+
   hb_object_header_t header;
   impl_t s;