diff --git a/include/boost/uuid/detail/nil_uuid.hpp b/include/boost/uuid/detail/nil_uuid.hpp
index 2371823..64124b1 100644
--- a/include/boost/uuid/detail/nil_uuid.hpp
+++ b/include/boost/uuid/detail/nil_uuid.hpp
@@ -10,9 +10,9 @@
 namespace boost {
 namespace uuids {
 
-inline uuid nil_uuid() noexcept
+constexpr uuid nil_uuid() noexcept
 {
-    return {{}};
+    return {};
 }
 
 }} // namespace boost::uuids
diff --git a/include/boost/uuid/namespaces.hpp b/include/boost/uuid/namespaces.hpp
index 82c4ec7..7747e7a 100644
--- a/include/boost/uuid/namespaces.hpp
+++ b/include/boost/uuid/namespaces.hpp
@@ -7,41 +7,38 @@
 // https://www.boost.org/LICENSE_1_0.txt
 
 #include <boost/uuid/uuid.hpp>
+#include <boost/config.hpp>
 
 namespace boost {
 namespace uuids {
 namespace ns {
 
-inline uuid dns() noexcept
+BOOST_CXX14_CONSTEXPR inline uuid dns() noexcept
 {
-    uuid result = {{
+    return {{
         0x6b, 0xa7, 0xb8, 0x10, 0x9d, 0xad, 0x11, 0xd1,
         0x80, 0xb4, 0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8 }};
-    return result;
 }
 
-inline uuid url() noexcept
+BOOST_CXX14_CONSTEXPR inline uuid url() noexcept
 {
-    uuid result = {{
+    return {{
         0x6b, 0xa7, 0xb8, 0x11, 0x9d, 0xad, 0x11, 0xd1,
         0x80, 0xb4, 0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8 }};
-    return result;
 }
 
-inline uuid oid() noexcept
+BOOST_CXX14_CONSTEXPR inline uuid oid() noexcept
 {
-    uuid result = {{
+    return {{
         0x6b, 0xa7, 0xb8, 0x12, 0x9d, 0xad, 0x11, 0xd1,
         0x80, 0xb4, 0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8 }};
-    return result;
 }
 
-inline uuid x500dn() noexcept
+BOOST_CXX14_CONSTEXPR inline uuid x500dn() noexcept
 {
-    uuid result = {{
+    return {{
         0x6b, 0xa7, 0xb8, 0x14, 0x9d, 0xad, 0x11, 0xd1,
         0x80, 0xb4, 0x00, 0xc0, 0x4f, 0xd4, 0x30, 0xc8 }};
-    return result;
 }
 
 }}} // namespace boost::uuids::ns
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 996f73b..42104ae 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -85,5 +85,6 @@ boost_test(TYPE run SOURCES test_constants.cpp)
 
 boost_test(TYPE compile SOURCES test_uuid_cx.cpp)
 boost_test(TYPE run SOURCES test_string_generator_cx.cpp)
+boost_test(TYPE run SOURCES test_constants_cx.cpp)
 
 boost_test(TYPE run SOURCES quick.cpp)
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index dcad707..b09cb0d 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -211,6 +211,7 @@ run test_constants.cpp ;
 
 compile test_uuid_cx.cpp ;
 run test_string_generator_cx.cpp ;
+run test_constants_cx.cpp ;
 
 # 'quick' test for CI
 
diff --git a/test/test_constants_cx.cpp b/test/test_constants_cx.cpp
new file mode 100644
index 0000000..23058eb
--- /dev/null
+++ b/test/test_constants_cx.cpp
@@ -0,0 +1,39 @@
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/uuid/constants.hpp>
+#include <boost/uuid/uuid.hpp>
+#include <boost/uuid/uuid_io.hpp>
+#include <boost/uuid/string_generator.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if defined(BOOST_NO_CXX14_CONSTEXPR)
+
+BOOST_PRAGMA_MESSAGE("Skipping test because BOOST_NO_CXX14_CONSTEXPR is defined")
+int main() {}
+
+#else
+
+using namespace boost::uuids;
+
+constexpr auto u1 = ns::dns();
+constexpr auto u2 = ns::url();
+constexpr auto u3 = ns::oid();
+constexpr auto u4 = ns::x500dn();
+constexpr auto u5 = nil_uuid();
+
+int main()
+{
+    BOOST_TEST_EQ( u1, string_generator()("6ba7b810-9dad-11d1-80b4-00c04fd430c8"));
+    BOOST_TEST_EQ( u2, string_generator()("6ba7b811-9dad-11d1-80b4-00c04fd430c8"));
+    BOOST_TEST_EQ( u3, string_generator()("6ba7b812-9dad-11d1-80b4-00c04fd430c8"));
+    BOOST_TEST_EQ( u4, string_generator()("6ba7b814-9dad-11d1-80b4-00c04fd430c8"));
+    BOOST_TEST_EQ( u5, string_generator()("00000000-0000-0000-0000-000000000000"));
+
+    return boost::report_errors();
+}
+
+#endif