diff --git a/src/Data/Binary.hs b/src/Data/Binary.hs
index 899ea633f67a53be361200906cfd59a10f249881..36d1caa717038439ec09cc617440f3f307c38d3a 100644
--- a/src/Data/Binary.hs
+++ b/src/Data/Binary.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP, FlexibleInstances #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      : Data.Binary
diff --git a/src/Data/Binary/Builder.hs b/src/Data/Binary/Builder.hs
index c7f8b6519d2d4f0b9a865e1886b1feace25f436e..ec6a8a85236b21ac8ff2fbbde2d9aad2f32e3290 100644
--- a/src/Data/Binary/Builder.hs
+++ b/src/Data/Binary/Builder.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# OPTIONS_GHC -fglasgow-exts #-}
 -- for unboxed shifts
 
diff --git a/src/Data/Binary/Get.hs b/src/Data/Binary/Get.hs
index 8c80f41a1fdc98516039126b01545a678cb327ed..e555410b349ac46735d900e66fd58683e3479618 100644
--- a/src/Data/Binary/Get.hs
+++ b/src/Data/Binary/Get.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# OPTIONS_GHC -fglasgow-exts #-}
 -- for unboxed shifts