diff --git a/src/Data/HexString.hs b/src/Data/HexString.hs
index f8d8d24..f1d1968 100644
--- a/src/Data/HexString.hs
+++ b/src/Data/HexString.hs
@@ -6,7 +6,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 
 module Data.HexString
-  ( HexString
+  ( HexString(..)
   , hexString
   , fromBinary
   , toBinary