diff --git a/System/Console/Docopt/Public.hs b/System/Console/Docopt/Public.hs
index f9dfd34..cf6d059 100644
--- a/System/Console/Docopt/Public.hs
+++ b/System/Console/Docopt/Public.hs
@@ -190,7 +190,7 @@ isPresentM :: Monad m => Arguments -> Option -> m Bool
 isPresentM args o = return $ isPresent args o
 
 {-# DEPRECATED getFirstArg "Use 'getAllArgs' instead" #-}
-getFirstArg :: Monad m => Arguments -> Option -> m String
+getFirstArg :: MonadFail m => Arguments -> Option -> m String
 getFirstArg args opt =
   let failure = fail $ "no argument given: " ++ show opt
   in  case opt `M.lookup` args of
diff --git a/System/Console/Docopt/QQ.hs b/System/Console/Docopt/QQ.hs
index 81027fb..a468231 100644
--- a/System/Console/Docopt/QQ.hs
+++ b/System/Console/Docopt/QQ.hs
@@ -56,7 +56,9 @@ docopt = QuasiQuoter { quoteExp  = docoptExp
                      , quotePat  = unsupported "Pattern"
                      , quoteType = unsupported "Type"
                      }
-    where unsupported = fail . (++ " context unsupported")
+    where unsupported :: String -> String -> Q a
+          unsupported qqType _ = do
+            fail $ (qqType ++ " context unsupported")
 
 -- | Same as 'docopt', but parses the given file instead of a literal
 -- string.
diff --git a/docopt.cabal b/docopt.cabal
index 5e043d6..32f2c06 100644
--- a/docopt.cabal
+++ b/docopt.cabal
@@ -43,7 +43,7 @@ library
                       System.Console.Docopt.OptParse
                       System.Console.Docopt.Public
 
-  build-depends:      base >= 4.0 && < 5.0,
+  build-depends:      base >= 4.9 && < 5.0,
                       parsec >= 3.1.0,
                       containers
 
diff --git a/stack.yaml b/stack.yaml
index e689536..39ae7e3 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,7 +1,7 @@
 # For advanced use and comprehensive documentation of the format, please see:
 # http://docs.haskellstack.org/en/stable/yaml_configuration/
 
-resolver: lts-7.4
+resolver: lts-16.20
 
 packages:
   - '.'