diff --git a/include/boost/system/detail/error_category.hpp b/include/boost/system/detail/error_category.hpp
index 3fd0ed6..2226678 100644
--- a/include/boost/system/detail/error_category.hpp
+++ b/include/boost/system/detail/error_category.hpp
@@ -27,21 +27,30 @@ namespace boost
 namespace system
 {
 
+class error_category;
 class error_code;
 class error_condition;
 
+std::size_t hash_value( error_code const & ec );
+
+namespace detail
+{
+
+BOOST_SYSTEM_CONSTEXPR bool failed_impl( int ev, error_category const & cat );
+
+} // namespace detail
+
 #if ( defined( BOOST_GCC ) && BOOST_GCC >= 40600 ) || defined( BOOST_CLANG )
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
 #endif
 
-std::size_t hash_value( error_code const & ec );
-
 class BOOST_SYMBOL_VISIBLE error_category
 {
 private:
 
     friend std::size_t hash_value( error_code const & ec );
+    friend BOOST_SYSTEM_CONSTEXPR bool detail::failed_impl( int ev, error_category const & cat );
 
 #if !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
 public:
@@ -97,7 +106,10 @@ public:
     virtual std::string message( int ev ) const = 0;
     virtual char const * message( int ev, char * buffer, std::size_t len ) const BOOST_NOEXCEPT;
 
-    virtual bool failed( int ev ) const BOOST_NOEXCEPT;
+    virtual bool failed( int ev ) const BOOST_NOEXCEPT
+    {
+        return ev != 0;
+    }
 
     BOOST_SYSTEM_CONSTEXPR bool operator==( const error_category & rhs ) const BOOST_NOEXCEPT
     {
@@ -140,6 +152,26 @@ public:
 #pragma GCC diagnostic pop
 #endif
 
+namespace detail
+{
+
+static const boost::ulong_long_type generic_category_id = ( boost::ulong_long_type( 0xB2AB117A ) << 32 ) + 0x257EDF0D;
+static const boost::ulong_long_type system_category_id = ( boost::ulong_long_type( 0x8FAFD21E ) << 32 ) + 0x25C5E09B;
+
+BOOST_SYSTEM_CONSTEXPR inline bool failed_impl( int ev, error_category const & cat )
+{
+    if( cat.id_ == system_category_id || cat.id_ == generic_category_id )
+    {
+        return ev != 0;
+    }
+    else
+    {
+        return cat.failed( ev );
+    }
+}
+
+} // namespace detail
+
 } // namespace system
 
 } // namespace boost
diff --git a/include/boost/system/detail/generic_category.hpp b/include/boost/system/detail/generic_category.hpp
index 4341c9e..01f5687 100644
--- a/include/boost/system/detail/generic_category.hpp
+++ b/include/boost/system/detail/generic_category.hpp
@@ -36,10 +36,8 @@ class BOOST_SYMBOL_VISIBLE generic_error_category: public error_category
 {
 public:
 
-    // clang++ 3.8 and below: initialization of const object
-    // requires a user-provided default constructor
     BOOST_SYSTEM_CONSTEXPR generic_error_category() BOOST_NOEXCEPT:
-        error_category( ( boost::ulong_long_type( 0xB2AB117A ) << 32 ) + 0x257EDF0D )
+        error_category( detail::generic_category_id )
     {
     }
 
diff --git a/include/boost/system/detail/system_category.hpp b/include/boost/system/detail/system_category.hpp
index d2ddf70..8e9d69b 100644
--- a/include/boost/system/detail/system_category.hpp
+++ b/include/boost/system/detail/system_category.hpp
@@ -37,7 +37,7 @@ class BOOST_SYMBOL_VISIBLE system_error_category: public error_category
 public:
 
     BOOST_SYSTEM_CONSTEXPR system_error_category() BOOST_NOEXCEPT:
-        error_category( ( boost::ulong_long_type( 0x8FAFD21E ) << 32 ) + 0x25C5E09B )
+        error_category( detail::system_category_id )
     {
     }
 
diff --git a/include/boost/system/error_code.hpp b/include/boost/system/error_code.hpp
index 2ca6b92..7e92edc 100644
--- a/include/boost/system/error_code.hpp
+++ b/include/boost/system/error_code.hpp
@@ -109,36 +109,6 @@ static const error_category & native_ecat BOOST_ATTRIBUTE_UNUSED = system_catego
 
 #endif
 
-namespace detail
-{
-
-// failed_impl
-
-#if !defined(BOOST_SYSTEM_HAS_CONSTEXPR)
-
-inline bool failed_impl( int ev, error_category const & cat )
-{
-    return cat.failed( ev );
-}
-
-#else
-
-BOOST_SYSTEM_CONSTEXPR inline bool failed_impl( int ev, error_category const & cat )
-{
-    if( cat == system_category() || cat == generic_category() )
-    {
-        return ev != 0;
-    }
-    else
-    {
-        return cat.failed( ev );
-    }
-}
-
-#endif
-
-} // namespace detail
-
 // class error_condition
 
 // error_conditions are portable, error_codes are system or library specific
@@ -602,11 +572,6 @@ inline char const * error_category::message( int ev, char * buffer, std::size_t
 #endif
 }
 
-inline bool error_category::failed( int ev ) const BOOST_NOEXCEPT
-{
-    return ev != 0;
-}
-
 } // namespace system
 
 } // namespace boost