diff --git a/include/boost/system/result.hpp b/include/boost/system/result.hpp
index db09455..762afa3 100644
--- a/include/boost/system/result.hpp
+++ b/include/boost/system/result.hpp
@@ -659,6 +659,13 @@ public:
     }
 };
 
+#if defined(BOOST_NO_CXX17_INLINE_VARIABLES)
+
+template<class E> constexpr in_place_value_t result<void, E>::in_place_value;
+template<class E> constexpr in_place_error_t result<void, E>::in_place_error;
+
+#endif
+
 template<class Ch, class Tr, class E> std::basic_ostream<Ch, Tr>& operator<<( std::basic_ostream<Ch, Tr>& os, result<void, E> const & r )
 {
     if( r.has_value() )
@@ -892,6 +899,13 @@ public:
     }
 };
 
+#if defined(BOOST_NO_CXX17_INLINE_VARIABLES)
+
+template<class U, class E> constexpr in_place_value_t result<U&, E>::in_place_value;
+template<class U, class E> constexpr in_place_error_t result<U&, E>::in_place_error;
+
+#endif
+
 // operator|
 
 namespace detail