diff --git a/include/boost/system/detail/error_condition.hpp b/include/boost/system/detail/error_condition.hpp
index 5d6840f..fb9f844 100644
--- a/include/boost/system/detail/error_condition.hpp
+++ b/include/boost/system/detail/error_condition.hpp
@@ -14,6 +14,8 @@
 #include <boost/system/detail/generic_category.hpp>
 #include <boost/system/detail/enable_if.hpp>
 #include <boost/system/is_error_condition_enum.hpp>
+#include <boost/system/detail/config.hpp>
+#include <boost/config.hpp>
 
 namespace boost
 {
@@ -152,6 +154,11 @@ public:
 #endif
 };
 
+BOOST_SYSTEM_CONSTEXPR inline bool operator!=( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT
+{
+    return !( lhs == rhs );
+}
+
 } // namespace system
 
 } // namespace boost
diff --git a/include/boost/system/error_code.hpp b/include/boost/system/error_code.hpp
index 9944a6f..c7e745f 100644
--- a/include/boost/system/error_code.hpp
+++ b/include/boost/system/error_code.hpp
@@ -87,11 +87,6 @@ inline system::error_code& throws()
 namespace system
 {
 
-BOOST_SYSTEM_CONSTEXPR inline bool operator!=( const error_condition & lhs, const error_condition & rhs ) BOOST_NOEXCEPT
-{
-    return !( lhs == rhs );
-}
-
 inline bool operator==( const error_code & code, const error_condition & condition ) BOOST_NOEXCEPT
 {
     return code.category().equivalent( code.value(), condition ) || condition.category().equivalent( code, condition.value() );