diff --git a/persona-idp.cabal b/persona-idp.cabal
--- a/persona-idp.cabal
+++ b/persona-idp.cabal
@@ -1,5 +1,5 @@
 name:                persona-idp
-version:             0.1.0.1
+version:             0.1.0.2
 synopsis:            Persona (BrowserID) Identity Provider
 description:
   .
@@ -49,7 +49,7 @@
     , blaze-markup >= 0.6
     , hamlet >= 1.2
     , http-types >= 0.8
-    , optparse-applicative == 0.9.*
+    , optparse-applicative >= 0.11
     , pem >= 0.2
     , scotty >= 0.8
     , shakespeare >= 2.0
diff --git a/src/Serve.hs b/src/Serve.hs
--- a/src/Serve.hs
+++ b/src/Serve.hs
@@ -46,7 +46,7 @@
 
 instance Command ServeOpts where
   parser = ServeOpts
-    <$> option
+    <$> option auto
       ( long "port"
       <> value 3000
       <> showDefault