diff --git a/include/boost/mp11/detail/mp_append.hpp b/include/boost/mp11/detail/mp_append.hpp
index 8a8f4d5..937d15e 100644
--- a/include/boost/mp11/detail/mp_append.hpp
+++ b/include/boost/mp11/detail/mp_append.hpp
@@ -26,6 +26,10 @@ template<class... L> struct mp_append_impl;
 
 #if BOOST_MP11_WORKAROUND( BOOST_MP11_MSVC, <= 1800 )
 
+template<class... L> struct mp_append_impl
+{
+};
+
 template<> struct mp_append_impl<>
 {
     using type = mp_list<>;
@@ -36,14 +40,31 @@ template<template<class...> class L, class... T> struct mp_append_impl<L<T...>>
     using type = L<T...>;
 };
 
-template<template<class...> class L1, class... T1, template<class...> class L2, class... T2, class... Lr> struct mp_append_impl<L1<T1...>, L2<T2...>, Lr...>
+template<template<class...> class L1, class... T1, template<class...> class L2, class... T2> struct mp_append_impl<L1<T1...>, L2<T2...>>
 {
-    using type = typename mp_append_impl<L1<T1..., T2...>, Lr...>::type;
+    using type = L1<T1..., T2...>;
+};
+
+template<template<class...> class L1, class... T1, template<class...> class L2, class... T2, template<class...> class L3, class... T3> struct mp_append_impl<L1<T1...>, L2<T2...>, L3<T3...>>
+{
+    using type = L1<T1..., T2..., T3...>;
+};
+
+template<template<class...> class L1, class... T1, template<class...> class L2, class... T2, template<class...> class L3, class... T3, template<class...> class L4, class... T4> struct mp_append_impl<L1<T1...>, L2<T2...>, L3<T3...>, L4<T4...>>
+{
+    using type = L1<T1..., T2..., T3..., T4...>;
+};
+
+template<template<class...> class L1, class... T1, template<class...> class L2, class... T2, template<class...> class L3, class... T3, template<class...> class L4, class... T4, template<class...> class L5, class... T5, class... Lr> struct mp_append_impl<L1<T1...>, L2<T2...>, L3<T3...>, L4<T4...>, L5<T5...>, Lr...>
+{
+    using type = typename mp_append_impl<L1<T1..., T2..., T3..., T4..., T5...>, Lr...>::type;
 };
 
 #else
 
-template<class L1 = mp_list<>, class L2 = mp_list<>, class L3 = mp_list<>, class L4 = mp_list<>, class L5 = mp_list<>, class L6 = mp_list<>, class L7 = mp_list<>, class L8 = mp_list<>, class L9 = mp_list<>, class L10 = mp_list<>, class L11 = mp_list<>> struct append_11_impl;
+template<class L1 = mp_list<>, class L2 = mp_list<>, class L3 = mp_list<>, class L4 = mp_list<>, class L5 = mp_list<>, class L6 = mp_list<>, class L7 = mp_list<>, class L8 = mp_list<>, class L9 = mp_list<>, class L10 = mp_list<>, class L11 = mp_list<>> struct append_11_impl
+{
+};
 
 template<
     template<class...> class L1, class... T1,
diff --git a/test/Jamfile b/test/Jamfile
index 5c9d59a..d385068 100644
--- a/test/Jamfile
+++ b/test/Jamfile
@@ -26,6 +26,7 @@ run mp_push_back.cpp ;
 run mp_rename.cpp ;
 run mp_append.cpp ;
 run mp_append_2.cpp ;
+run mp_append_sf.cpp ;
 run mp_replace_front.cpp ;
 run mp_replace_second.cpp ;
 run mp_replace_third.cpp ;
diff --git a/test/mp_append.cpp b/test/mp_append.cpp
index 25482c4..264359a 100644
--- a/test/mp_append.cpp
+++ b/test/mp_append.cpp
@@ -1,5 +1,5 @@
 
-//  Copyright 2015 Peter Dimov.
+// Copyright 2015 Peter Dimov.
 //
 // Distributed under the Boost Software License, Version 1.0.
 //
diff --git a/test/mp_append_sf.cpp b/test/mp_append_sf.cpp
new file mode 100644
index 0000000..80c417c
--- /dev/null
+++ b/test/mp_append_sf.cpp
@@ -0,0 +1,32 @@
+
+// Copyright 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/utility.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+
+int main()
+{
+    using boost::mp11::mp_append;
+    using boost::mp11::mp_valid;
+    using boost::mp11::mp_list;
+
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, void, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, void, void, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, void, void, void, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, void, void, void, void, void>));
+
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, mp_list<>, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, mp_list<>, mp_list<>, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, mp_list<>, mp_list<>, mp_list<>, void>));
+    BOOST_TEST_TRAIT_FALSE((mp_valid<mp_append, mp_list<>, mp_list<>, mp_list<>, mp_list<>, void>));
+
+    return boost::report_errors();
+}