diff --git a/Crypto/Internal/Endian.hs b/Crypto/Internal/Endian.hs
index 1fef507..497135b 100644
--- a/Crypto/Internal/Endian.hs
+++ b/Crypto/Internal/Endian.hs
@@ -14,7 +14,7 @@ module Crypto.Internal.Endian
 import Crypto.Internal.Compat (byteSwap64)
 import Data.Word (Word64)
 
-#ifndef ARCH_IS_LITTLE_ENDIAN
+#ifdef ARCH_IS_LITTLE_ENDIAN
 fromLE64 :: Word64 -> Word64
 fromLE64 = id