diff --git a/xxhash/xxhash.c b/xxhash/xxhash.c
index 511d994..808e4bc 100644
--- a/xxhash/xxhash.c
+++ b/xxhash/xxhash.c
@@ -191,7 +191,7 @@ static U64 XXH_read64(const void* memPtr)
 #if defined(_MSC_VER)     /* Visual Studio */
 #  define XXH_swap32 _byteswap_ulong
 #  define XXH_swap64 _byteswap_uint64
-#elif GCC_VERSION >= 403
+#elif GCC_VERSION >= 403 || __clang__
 #  define XXH_swap32 __builtin_bswap32
 #  define XXH_swap64 __builtin_bswap64
 #else