diff --git a/include/boost/unordered/detail/requires_cxx11.hpp b/include/boost/unordered/detail/requires_cxx11.hpp
new file mode 100644
index 00000000..b7c7b813
--- /dev/null
+++ b/include/boost/unordered/detail/requires_cxx11.hpp
@@ -0,0 +1,21 @@
+#ifndef BOOST_UNORDERED_DETAIL_REQUIRES_CXX11_HPP_INCLUDED
+#define BOOST_UNORDERED_DETAIL_REQUIRES_CXX11_HPP_INCLUDED
+
+// Copyright 2023 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if defined(BOOST_NO_CXX11_VARIADIC_TEMPLATES) || \
+    defined(BOOST_NO_CXX11_RVALUE_REFERENCES) || \
+    defined(BOOST_NO_CXX11_DECLTYPE) || \
+    defined(BOOST_NO_CXX11_CONSTEXPR) || \
+    defined(BOOST_NO_CXX11_NOEXCEPT)
+
+BOOST_PRAGMA_MESSAGE("C++03 support is deprecated in Boost.Unordered 1.82 and will be removed in Boost.Unordered 1.84.")
+
+#endif
+
+#endif // #ifndef BOOST_UNORDERED_DETAIL_REQUIRES_CXX11_HPP_INCLUDED
diff --git a/include/boost/unordered/unordered_map.hpp b/include/boost/unordered/unordered_map.hpp
index 6d05471c..8a8bc062 100644
--- a/include/boost/unordered/unordered_map.hpp
+++ b/include/boost/unordered/unordered_map.hpp
@@ -15,6 +15,7 @@
 #pragma once
 #endif
 
+#include <boost/unordered/detail/requires_cxx11.hpp>
 #include <boost/core/explicit_operator_bool.hpp>
 #include <boost/functional/hash.hpp>
 #include <boost/move/move.hpp>
diff --git a/include/boost/unordered/unordered_set.hpp b/include/boost/unordered/unordered_set.hpp
index 1bd4ba3d..23837b2d 100644
--- a/include/boost/unordered/unordered_set.hpp
+++ b/include/boost/unordered/unordered_set.hpp
@@ -15,6 +15,7 @@
 #pragma once
 #endif
 
+#include <boost/unordered/detail/requires_cxx11.hpp>
 #include <boost/core/explicit_operator_bool.hpp>
 #include <boost/functional/hash.hpp>
 #include <boost/move/move.hpp>