--- a/src/Options/Declarative.hs
+++ b/src/Options/Declarative.hs
@@ -45,6 +45,7 @@
 import           Control.Applicative
 import           Control.Monad
 import           Control.Monad.Catch
+import Control.Monad.Fix
 import           Control.Monad.Reader
 import           Data.List
 import           Data.Maybe