diff --git a/include/rapidjson/rapidjson.h b/include/rapidjson/rapidjson.h
index 0c41ab655..b06e82b01 100644
--- a/include/rapidjson/rapidjson.h
+++ b/include/rapidjson/rapidjson.h
@@ -241,8 +241,12 @@
     alignment. User can customize by defining the RAPIDJSON_ALIGN function macro.,
 */
 #ifndef RAPIDJSON_ALIGN
+#if RAPIDJSON_64BIT == 1
+#define RAPIDJSON_ALIGN(x) ((x + 7u) & ~7u)
+#else
 #define RAPIDJSON_ALIGN(x) ((x + 3u) & ~3u)
 #endif
+#endif
 
 ///////////////////////////////////////////////////////////////////////////////
 // RAPIDJSON_UINT64_C2