diff --git a/test/Jamfile b/test/Jamfile
index 69938e1..f8edba8 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -403,3 +403,5 @@ run sp_owner_hash_value_test.cpp ;
 
 run wp_hash_test.cpp ;
 run wp_hash_test2.cpp ;
+
+run wp_unordered_test.cpp ;
diff --git a/test/wp_unordered_test.cpp b/test/wp_unordered_test.cpp
new file mode 100644
index 0000000..0d35d58
--- /dev/null
+++ b/test/wp_unordered_test.cpp
@@ -0,0 +1,87 @@
+// Copyright 2011, 2020 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/weak_ptr.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+
+#if defined(BOOST_NO_CXX11_HDR_UNORDERED_SET)
+
+int main() {}
+
+#else
+
+#include <unordered_set>
+
+int main()
+{
+    std::unordered_set< boost::weak_ptr<void> > set;
+
+    boost::shared_ptr<int> p1( (int*)0 );
+    boost::shared_ptr<int> p2( p1 );
+    boost::shared_ptr<void> p3( p1 );
+
+    set.insert( p1 );
+    set.insert( p2 );
+    set.insert( p3 );
+
+    BOOST_TEST_EQ( set.size(), 1 );
+
+    boost::weak_ptr<int> q1( p1 );
+    boost::weak_ptr<int> q2( p2 );
+    boost::weak_ptr<void> q3( p3 );
+    boost::weak_ptr<int> q4( q2 );
+    boost::weak_ptr<void> q5( q3 );
+
+    set.insert( q1 );
+    set.insert( q2 );
+    set.insert( q3 );
+    set.insert( q4 );
+    set.insert( q5 );
+
+    BOOST_TEST_EQ( set.size(), 1 );
+
+    boost::shared_ptr<int> p6( (int*)0 );
+
+    set.insert( p6 );
+
+    BOOST_TEST_EQ( set.size(), 2 );
+
+    boost::weak_ptr<int> q6( p6 );
+
+    set.insert( q6 );
+
+    BOOST_TEST_EQ( set.size(), 2 );
+
+    BOOST_TEST_EQ( set.count( q1 ), 1 );
+    BOOST_TEST_EQ( set.count( q2 ), 1 );
+    BOOST_TEST_EQ( set.count( q3 ), 1 );
+    BOOST_TEST_EQ( set.count( q4 ), 1 );
+    BOOST_TEST_EQ( set.count( q5 ), 1 );
+    BOOST_TEST_EQ( set.count( q6 ), 1 );
+
+    boost::shared_ptr<int> p7( (int*)0 );
+    boost::weak_ptr<int> q7( p7 );
+
+    BOOST_TEST_EQ( set.count( q7 ), 0 );
+
+    p1.reset();
+    p2.reset();
+    p3.reset();
+    p6.reset();
+    p7.reset();
+
+    BOOST_TEST_EQ( set.count( q1 ), 1 );
+    BOOST_TEST_EQ( set.count( q2 ), 1 );
+    BOOST_TEST_EQ( set.count( q3 ), 1 );
+    BOOST_TEST_EQ( set.count( q4 ), 1 );
+    BOOST_TEST_EQ( set.count( q5 ), 1 );
+    BOOST_TEST_EQ( set.count( q6 ), 1 );
+    BOOST_TEST_EQ( set.count( q7 ), 0 );
+
+    return boost::report_errors();
+}
+
+#endif // #if defined(BOOST_NO_CXX11_HDR_UNORDERED_SET)