diff --git a/config.h b/config.h
index 0d99df57..8c58004d 100644
--- a/config.h
+++ b/config.h
@@ -217,7 +217,7 @@ typedef unsigned int word32;
 #if defined(_MSC_VER) || defined(__BORLANDC__)
 	typedef unsigned __int64 word64;
 	#define W64LIT(x) x##ui64
-#elif ((__arm64__ || __aarch64__) && (_LP64 || __LP64__))
+#elif (_LP64 || __LP64__) && ((__arm64__ || __aarch64__) || !defined(CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562))
 	typedef unsigned long word64;
 	#define W64LIT(x) x##UL
 #else
diff --git a/config.recommend b/config.recommend
index 966a6da8..2b28d541 100644
--- a/config.recommend
+++ b/config.recommend
@@ -217,7 +217,7 @@ typedef unsigned int word32;
 #if defined(_MSC_VER) || defined(__BORLANDC__)
 	typedef unsigned __int64 word64;
 	#define W64LIT(x) x##ui64
-#elif ((__arm64__ || __aarch64__) && (_LP64 || __LP64__))
+#elif (_LP64 || __LP64__) && ((__arm64__ || __aarch64__) || !defined(CRYPTOPP_MAINTAIN_BACKWARDS_COMPATIBILITY_562))
 	typedef unsigned long word64;
 	#define W64LIT(x) x##UL
 #else