diff --git a/Options/Applicative/Builder.hs b/Options/Applicative/Builder.hs
--- a/Options/Applicative/Builder.hs
+++ b/Options/Applicative/Builder.hs
@@ -55,6 +55,7 @@
   -- * Internals
   Mod,
   HasName,
+  HasCompleter,
   OptionFields,
   FlagFields,
   CommandFields,
@@ -364,11 +365,11 @@
 
 -- | Builder for an option taking a 'String' argument.
 strOption :: Mod OptionFields String -> Parser String
-strOption m = nullOption $ m & reader str
+strOption m = nullOption $ reader str & m
 
 -- | Builder for an option using the 'auto' reader.
 option :: Read a => Mod OptionFields a -> Parser a
-option m = nullOption $ m & reader auto
+option m = nullOption $ reader auto & m
 
 -- | Modifier for 'ParserInfo'.
 newtype InfoMod a = InfoMod
diff --git a/optparse-applicative.cabal b/optparse-applicative.cabal
--- a/optparse-applicative.cabal
+++ b/optparse-applicative.cabal
@@ -1,5 +1,5 @@
 name:                optparse-applicative
-version:             0.4.0
+version:             0.4.1
 synopsis:            Utilities and combinators for parsing command line options
 description:
     Here is a simple example of an applicative option parser:
diff --git a/tests/Tests.hs b/tests/Tests.hs
--- a/tests/Tests.hs
+++ b/tests/Tests.hs
@@ -191,5 +191,17 @@
     Right val ->
       assertFailure $ "unexpected result " ++ show val
 
+case_issue_19 :: Assertion
+case_issue_19 = do
+  let p = option
+        ( short 'x'
+        & reader (Just . str)
+        & value Nothing )
+      i = info (p <**> helper) idm
+      result = run i ["-x", "foo"]
+  case result of
+    Left _ -> assertFailure "unexpected parse error"
+    Right r -> Just "foo" @=? r
+
 main :: IO ()
 main = $(defaultMainGenerator)