diff --git a/contrib/rapidjson/include/rapidjson/document.h b/contrib/rapidjson/include/rapidjson/document.h
index 4c94555b7..7079ef8a2 100644
--- a/contrib/rapidjson/include/rapidjson/document.h
+++ b/contrib/rapidjson/include/rapidjson/document.h
@@ -557,12 +557,14 @@ public:
             flags_ |= kIntFlag;
     }
 
+#if !defined(__x86_64__)
     //! Constructor for size_t value.
     explicit GenericValue( size_t u ) RAPIDJSON_NOEXCEPT : data_(), flags_( kNumberUintFlag ) {
         data_.n.u64 = u;
         if ( !( u&0x80000000 ) )
             flags_ |= kIntFlag|kInt64Flag;
     }
+#endif
 #endif
 
     //! Constructor for double value.