diff --git a/include/boost/mp11/detail/mpl_common.hpp b/include/boost/mp11/detail/mpl_common.hpp
new file mode 100644
index 0000000..208885c
--- /dev/null
+++ b/include/boost/mp11/detail/mpl_common.hpp
@@ -0,0 +1,160 @@
+#ifndef BOOST_MP11_DETAIL_MPL_COMMON_HPP_INCLUDED
+#define BOOST_MP11_DETAIL_MPL_COMMON_HPP_INCLUDED
+
+// Copyright 2017, 2019 Peter Dimov.
+//
+// Distributed under the Boost Software License, Version 1.0.
+//
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/algorithm.hpp>
+
+namespace boost
+{
+namespace mpl
+{
+
+struct forward_iterator_tag;
+
+namespace aux
+{
+
+struct mp11_tag {};
+
+template<class L> struct mp11_iterator
+{
+    using category = forward_iterator_tag;
+
+    using type = mp11::mp_first<L>;
+    using next = mp11_iterator<mp11::mp_rest<L>>;
+};
+
+} // namespace aux
+
+// at
+
+template< typename Tag > struct at_impl;
+
+template<> struct at_impl<aux::mp11_tag>
+{
+    template<class L, class I> struct apply
+    {
+        using type = mp11::mp_at<L, I>;
+    };
+};
+
+// back
+
+template< typename Tag > struct back_impl;
+
+template<> struct back_impl<aux::mp11_tag>
+{
+    template<class L> struct apply
+    {
+        using N = mp11::mp_size<L>;
+        using type = mp11::mp_at_c<L, N::value - 1>;
+    };
+};
+
+// begin
+
+template< typename Tag > struct begin_impl;
+
+template<> struct begin_impl<aux::mp11_tag>
+{
+    template<class L> struct apply
+    {
+        using type = aux::mp11_iterator<L>;
+    };
+};
+
+// clear
+
+template< typename Tag > struct clear_impl;
+
+template<> struct clear_impl<aux::mp11_tag>
+{
+    template<class L> struct apply
+    {
+        using type = mp11::mp_clear<L>;
+    };
+};
+
+// end
+
+template< typename Tag > struct end_impl;
+
+template<> struct end_impl<aux::mp11_tag>
+{
+    template<class L> struct apply
+    {
+        using type = aux::mp11_iterator<mp11::mp_clear<L>>;
+    };
+};
+
+// front
+
+template< typename Tag > struct front_impl;
+
+template<> struct front_impl<aux::mp11_tag>
+{
+    template<class L> struct apply
+    {
+        using type = mp11::mp_front<L>;
+    };
+};
+
+// pop_front
+
+template< typename Tag > struct pop_front_impl;
+
+template<> struct pop_front_impl<aux::mp11_tag>
+{
+    template<class L> struct apply
+    {
+        using type = mp11::mp_pop_front<L>;
+    };
+};
+
+// push_back
+
+template< typename Tag > struct push_back_impl;
+
+template<> struct push_back_impl<aux::mp11_tag>
+{
+    template<class L, class T> struct apply
+    {
+        using type = mp11::mp_push_back<L, T>;
+    };
+};
+
+// push_front
+
+template< typename Tag > struct push_front_impl;
+
+template<> struct push_front_impl<aux::mp11_tag>
+{
+    template<class L, class T> struct apply
+    {
+        using type = mp11::mp_push_front<L, T>;
+    };
+};
+
+// size
+
+template< typename Tag > struct size_impl;
+
+template<> struct size_impl<aux::mp11_tag>
+{
+    template<class L> struct apply
+    {
+        using type = mp11::mp_size<L>;
+    };
+};
+
+} // namespace mpl
+} // namespace boost
+
+#endif // #ifndef BOOST_MP11_DETAIL_MPL_COMMON_HPP_INCLUDED
diff --git a/include/boost/mp11/mpl.hpp b/include/boost/mp11/mpl.hpp
index 0e836cb..994705f 100644
--- a/include/boost/mp11/mpl.hpp
+++ b/include/boost/mp11/mpl.hpp
@@ -1,175 +1,14 @@
 #ifndef BOOST_MP11_MPL_HPP_INCLUDED
 #define BOOST_MP11_MPL_HPP_INCLUDED
 
-// Copyright 2017 Peter Dimov.
+// Copyright 2017, 2019 Peter Dimov.
 //
 // Distributed under the Boost Software License, Version 1.0.
 //
 // See accompanying file LICENSE_1_0.txt or copy at
 // http://www.boost.org/LICENSE_1_0.txt
 
-#include <boost/mp11/list.hpp>
-#include <boost/mp11/algorithm.hpp>
-#include <tuple>
-
-namespace boost
-{
-namespace mpl
-{
-
-struct forward_iterator_tag;
-
-namespace aux
-{
-
-struct mp11_tag {};
-
-template<class L> struct mp11_iterator
-{
-    using category = forward_iterator_tag;
-
-    using type = mp11::mp_first<L>;
-    using next = mp11_iterator<mp11::mp_rest<L>>;
-};
-
-} // namespace aux
-
-// at
-
-template< typename Tag > struct at_impl;
-
-template<> struct at_impl<aux::mp11_tag>
-{
-    template<class L, class I> struct apply
-    {
-        using type = mp11::mp_at<L, I>;
-    };
-};
-
-// back
-
-template< typename Tag > struct back_impl;
-
-template<> struct back_impl<aux::mp11_tag>
-{
-    template<class L> struct apply
-    {
-        using N = mp11::mp_size<L>;
-        using type = mp11::mp_at_c<L, N::value - 1>;
-    };
-};
-
-// begin
-
-template< typename Tag > struct begin_impl;
-
-template<> struct begin_impl<aux::mp11_tag>
-{
-    template<class L> struct apply
-    {
-        using type = aux::mp11_iterator<L>;
-    };
-};
-
-// clear
-
-template< typename Tag > struct clear_impl;
-
-template<> struct clear_impl<aux::mp11_tag>
-{
-    template<class L> struct apply
-    {
-        using type = mp11::mp_clear<L>;
-    };
-};
-
-// end
-
-template< typename Tag > struct end_impl;
-
-template<> struct end_impl<aux::mp11_tag>
-{
-    template<class L> struct apply
-    {
-        using type = aux::mp11_iterator<mp11::mp_clear<L>>;
-    };
-};
-
-// front
-
-template< typename Tag > struct front_impl;
-
-template<> struct front_impl<aux::mp11_tag>
-{
-    template<class L> struct apply
-    {
-        using type = mp11::mp_front<L>;
-    };
-};
-
-// pop_front
-
-template< typename Tag > struct pop_front_impl;
-
-template<> struct pop_front_impl<aux::mp11_tag>
-{
-    template<class L> struct apply
-    {
-        using type = mp11::mp_pop_front<L>;
-    };
-};
-
-// push_back
-
-template< typename Tag > struct push_back_impl;
-
-template<> struct push_back_impl<aux::mp11_tag>
-{
-    template<class L, class T> struct apply
-    {
-        using type = mp11::mp_push_back<L, T>;
-    };
-};
-
-// push_front
-
-template< typename Tag > struct push_front_impl;
-
-template<> struct push_front_impl<aux::mp11_tag>
-{
-    template<class L, class T> struct apply
-    {
-        using type = mp11::mp_push_front<L, T>;
-    };
-};
-
-// sequence_tag
-
-template< typename Sequence > struct sequence_tag;
-
-template<class... T> struct sequence_tag<mp11::mp_list<T...>>
-{
-    using type = aux::mp11_tag;
-};
-
-template<class... T> struct sequence_tag<std::tuple<T...>>
-{
-    using type = aux::mp11_tag;
-};
-
-// size
-
-template< typename Tag > struct size_impl;
-
-template<> struct size_impl<aux::mp11_tag>
-{
-    template<class L> struct apply
-    {
-        using type = mp11::mp_size<L>;
-    };
-};
-
-} // namespace mpl
-} // namespace boost
+#include <boost/mp11/mpl_list.hpp>
+#include <boost/mp11/mpl_tuple.hpp>
 
 #endif // #ifndef BOOST_MP11_MPL_HPP_INCLUDED
diff --git a/include/boost/mp11/mpl_list.hpp b/include/boost/mp11/mpl_list.hpp
new file mode 100644
index 0000000..643da43
--- /dev/null
+++ b/include/boost/mp11/mpl_list.hpp
@@ -0,0 +1,28 @@
+#ifndef BOOST_MP11_MPL_LIST_HPP_INCLUDED
+#define BOOST_MP11_MPL_LIST_HPP_INCLUDED
+
+// Copyright 2017, 2019 Peter Dimov.
+//
+// Distributed under the Boost Software License, Version 1.0.
+//
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/detail/mpl_common.hpp>
+
+namespace boost
+{
+namespace mpl
+{
+
+template< typename Sequence > struct sequence_tag;
+
+template<class... T> struct sequence_tag<mp11::mp_list<T...>>
+{
+    using type = aux::mp11_tag;
+};
+
+} // namespace mpl
+} // namespace boost
+
+#endif // #ifndef BOOST_MP11_MPL_LIST_HPP_INCLUDED
diff --git a/include/boost/mp11/mpl_tuple.hpp b/include/boost/mp11/mpl_tuple.hpp
new file mode 100644
index 0000000..b6900b1
--- /dev/null
+++ b/include/boost/mp11/mpl_tuple.hpp
@@ -0,0 +1,29 @@
+#ifndef BOOST_MP11_MPL_TUPLE_HPP_INCLUDED
+#define BOOST_MP11_MPL_TUPLE_HPP_INCLUDED
+
+// Copyright 2017, 2019 Peter Dimov.
+//
+// Distributed under the Boost Software License, Version 1.0.
+//
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/mp11/detail/mpl_common.hpp>
+#include <tuple>
+
+namespace boost
+{
+namespace mpl
+{
+
+template< typename Sequence > struct sequence_tag;
+
+template<class... T> struct sequence_tag<std::tuple<T...>>
+{
+    using type = aux::mp11_tag;
+};
+
+} // namespace mpl
+} // namespace boost
+
+#endif // #ifndef BOOST_MP11_MPL_TUPLE_HPP_INCLUDED