diff --git a/src/Language/Json/Parser.hs b/src/Language/Json/Parser.hs
index d12769a..7e70472 100644
--- a/src/Language/Json/Parser.hs
+++ b/src/Language/Json/Parser.hs
@@ -9,7 +9,7 @@ import Data.Functor (($>))
 newtype Parser a = Parser (Text -> Reply a)
 
 data Reply a
-  = Done Text a -- rest, result
+  = Done !Text !a -- rest, result
   | Fail
 
 instance Functor Reply where