diff --git a/set/dset.hpp b/set/dset.hpp
index fea61085..79b33c00 100644
--- a/set/dset.hpp
+++ b/set/dset.hpp
@@ -82,7 +82,7 @@ namespace cruft::set {
         /// supplied store.
         bool contains (dset const &rhs) const
         {
-            return contains (rhs.m_data);
+            return contains (std::span<ValueT const> {rhs.m_data.data (), rhs.m_size});
         }
 
         std::size_t count (ValueT const &val) const