diff --git a/cabal-debian.cabal b/cabal-debian.cabal
--- a/cabal-debian.cabal
+++ b/cabal-debian.cabal
@@ -1,5 +1,5 @@
 Name:           cabal-debian
-Version:        4.35.8
+Version:        4.35.9
 Copyright:      Copyright (c) 2007-2014, David Fox, Jeremy Shaw
 License:        BSD3
 License-File:   LICENSE
diff --git a/src/Debian/Debianize/Optparse.hs b/src/Debian/Debianize/Optparse.hs
--- a/src/Debian/Debianize/Optparse.hs
+++ b/src/Debian/Debianize/Optparse.hs
@@ -180,7 +180,7 @@
 nameAddrR = either fail return =<< parseMaintainer <$> O.str
 
 relationsR :: O.ReadM Relations
-relationsR = either (fail . show) return =<< parseRelations <$> O.str
+relationsR = either (fail . show) return =<< parseRelations <$> (O.str :: O.ReadM String)
 
 mappingR :: O.ReadM (String, Relations)
 mappingR = span (/= ':') <$> O.str >>= \case
@@ -313,7 +313,7 @@
     ]
 
 debianVersionP :: O.Parser (Maybe DebianVersion)
-debianVersionP = O.option (Just . parseDebianVersion' <$> O.str) m where
+debianVersionP = O.option (Just . parseDebianVersion' <$> (O.str :: O.ReadM String)) m where
   m = O.help helpMsg
       <> O.long "deb-version"
       <> O.metavar "DEBIANVERSION"