diff --git a/include/boost/system/error_code.hpp b/include/boost/system/error_code.hpp
index 9fb7de3..0881d64 100644
--- a/include/boost/system/error_code.hpp
+++ b/include/boost/system/error_code.hpp
@@ -783,11 +783,11 @@ inline std::size_t hash_value( error_code const & ec )
 {
     error_category const & cat = ec.category();
 
-    boost::ulong_long_type id = cat.id_;
+    boost::ulong_long_type id_ = cat.id_;
 
-    if( id == 0 )
+    if( id_ == 0 )
     {
-        id = reinterpret_cast<boost::uintptr_t>( &cat );
+        id_ = reinterpret_cast<boost::uintptr_t>( &cat );
     }
 
     boost::ulong_long_type hv = ( boost::ulong_long_type( 0xCBF29CE4 ) << 32 ) + 0x84222325;
@@ -795,7 +795,7 @@ inline std::size_t hash_value( error_code const & ec )
 
     // id
 
-    hv ^= id;
+    hv ^= id_;
     hv *= prime;
 
     // value