diff --git a/include/boost/core/bit.hpp b/include/boost/core/bit.hpp
index 92489c6..755ad40 100644
--- a/include/boost/core/bit.hpp
+++ b/include/boost/core/bit.hpp
@@ -15,7 +15,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 #include <boost/config.hpp>
 #include <boost/cstdint.hpp>
 #include <limits>
diff --git a/include/boost/core/cmath.hpp b/include/boost/core/cmath.hpp
index b238bdf..9cfe26e 100644
--- a/include/boost/core/cmath.hpp
+++ b/include/boost/core/cmath.hpp
@@ -20,7 +20,7 @@
 
 #if defined(BOOST_CORE_USE_GENERIC_CMATH) || (!defined(_MSC_VER) && !defined(FP_SUBNORMAL))
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 #include <boost/cstdint.hpp>
 #include <limits>
 #include <cstring>
diff --git a/include/boost/core/static_assert.hpp b/include/boost/core/detail/static_assert.hpp
similarity index 83%
rename from include/boost/core/static_assert.hpp
rename to include/boost/core/detail/static_assert.hpp
index 126b257..f62f767 100644
--- a/include/boost/core/static_assert.hpp
+++ b/include/boost/core/detail/static_assert.hpp
@@ -1,5 +1,5 @@
-#ifndef BOOST_CORE_STATIC_ASSERT_HPP_INCLUDED
-#define BOOST_CORE_STATIC_ASSERT_HPP_INCLUDED
+#ifndef BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
 
 // Copyright 2025 Peter Dimov
 // Distributed under the Boost Software License, Version 1.0.
@@ -39,4 +39,4 @@ template<std::size_t> struct static_assert_test
 
 #endif
 
-#endif  // #ifndef BOOST_CORE_STATIC_ASSERT_HPP_INCLUDED
+#endif  // #ifndef BOOST_CORE_DETAIL_STATIC_ASSERT_HPP_INCLUDED
diff --git a/test/static_assert_fail.cpp b/test/static_assert_fail.cpp
index 6145cbc..03834c9 100644
--- a/test/static_assert_fail.cpp
+++ b/test/static_assert_fail.cpp
@@ -2,7 +2,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 
 BOOST_CORE_STATIC_ASSERT( sizeof(char[1]) != 1 );
 
diff --git a/test/static_assert_fail2.cpp b/test/static_assert_fail2.cpp
index 9f7f4d7..ae60a63 100644
--- a/test/static_assert_fail2.cpp
+++ b/test/static_assert_fail2.cpp
@@ -2,7 +2,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 
 struct X
 {
diff --git a/test/static_assert_fail3.cpp b/test/static_assert_fail3.cpp
index 09fb4a4..0126cf0 100644
--- a/test/static_assert_fail3.cpp
+++ b/test/static_assert_fail3.cpp
@@ -2,7 +2,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 
 int main()
 {
diff --git a/test/static_assert_fail4.cpp b/test/static_assert_fail4.cpp
index f381490..20b1fdd 100644
--- a/test/static_assert_fail4.cpp
+++ b/test/static_assert_fail4.cpp
@@ -2,7 +2,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 
 template<int C> struct X
 {
diff --git a/test/static_assert_test.cpp b/test/static_assert_test.cpp
index 6241d75..2f105bc 100644
--- a/test/static_assert_test.cpp
+++ b/test/static_assert_test.cpp
@@ -2,7 +2,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 
 BOOST_CORE_STATIC_ASSERT( sizeof(char[1]) == 1 );
 
diff --git a/test/static_assert_test2.cpp b/test/static_assert_test2.cpp
index b6e7de3..3896d42 100644
--- a/test/static_assert_test2.cpp
+++ b/test/static_assert_test2.cpp
@@ -2,7 +2,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 
 template<int A, int B> struct plus
 {
diff --git a/test/static_assert_test3.cpp b/test/static_assert_test3.cpp
index 177b6b4..85d43e1 100644
--- a/test/static_assert_test3.cpp
+++ b/test/static_assert_test3.cpp
@@ -2,7 +2,7 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/core/static_assert.hpp>
+#include <boost/core/detail/static_assert.hpp>
 
 template<int C> struct X
 {