diff --git a/src/Data/Amb.hs b/src/Data/Amb.hs
index e85f197df..5e384486b 100644
--- a/src/Data/Amb.hs
+++ b/src/Data/Amb.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE MultiParamTypeClasses, NoStrictData #-}
 module Data.Amb where
 
 import Control.Monad.Error.Class