diff --git a/app/Main.hs b/app/Main.hs
index 43f9c75..d71aedf 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -5,6 +5,8 @@ import Defaults
 import Defaults.Types (DomainName(..))
 
 import Options.Applicative
+import Relude.Extra (un)
+import Data.Text (unpack)
 
 -- | Main
 main :: IO ()
@@ -25,6 +27,7 @@ commands = hsubparser
                (DomainName <$> strArgument
                  (  metavar "DOMAIN..."
                  <> help "Domain(s) that will be watched."
+                 <> completer domainCompleter
                  )
                )
          <|> flag' (watch =<< domains)
@@ -45,8 +48,11 @@ commands = hsubparser
          (printKeys . DomainName <$> strArgument
            (  metavar "DOMAIN"
            <> help "A domain for which to list keys."
+           <> completer domainCompleter
            )
          )
          $ progDesc "List the current keys in a domain."
        )
   )
+    where
+      domainCompleter = listIOCompleter $ fmap (fmap unpack . un . toList) domains
diff --git a/package.yaml b/package.yaml
index 4c34a69..edd9cbc 100644
--- a/package.yaml
+++ b/package.yaml
@@ -42,6 +42,7 @@ executables:
     - -with-rtsopts=-N
     dependencies:
     - prefmanager
+    - relude
     - optparse-applicative
 
 tests:
diff --git a/prefmanager.cabal b/prefmanager.cabal
index 28f4eed..bb7755e 100644
--- a/prefmanager.cabal
+++ b/prefmanager.cabal
@@ -4,7 +4,7 @@ cabal-version: 1.12
 --
 -- see: https://github.com/sol/hpack
 --
--- hash: 4bc817bf57fae042a1b016e58f5362763ec47db040b12f0912db03d7ad80580f
+-- hash: 4f3ba99c73e2d565d8ad37f7906383a7069cf9a60542054cce281b52138c5c6c
 
 name:           prefmanager
 version:        0.1.0.0
@@ -63,6 +63,7 @@ executable prefmanager
       base-noprelude
     , optparse-applicative
     , prefmanager
+    , relude
   default-language: Haskell2010
 
 test-suite prefmanager-test