diff --git a/CHANGES.txt b/CHANGES.txt
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,5 +1,9 @@
 Changelog for HLint
 
+1.9.33
+    #240, remove type-incorrect "on" hint
+    #234, warn about join seq
+    #232, suggest <|> instead of mplus in a few cases
 1.9.32
     #53, require cpphs-1.20.1, has important fixes
     #224, treat select $ specially, as per esqueleto conventions
diff --git a/data/Default.hs b/data/Default.hs
--- a/data/Default.hs
+++ b/data/Default.hs
@@ -225,7 +225,6 @@
 warn "Redundant $" = (f $) ==> f
 hint = (\x -> y) ==> const y where _ = isAtom y && not (isWildcard y)
 warn "Redundant flip" = flip f x y ==> f y x where _ = isApp original
-hint = (\a b -> g (f a) (f b)) ==> g `Data.Function.on` f
 warn "Evaluate" = id x ==> x
 warn "Redundant id" = id . x ==> x
 warn "Redundant id" = x . id ==> x
@@ -374,6 +373,7 @@
 -- SEQ
 
 warn "Redundant seq" = x `seq` x ==> x
+warn "Redundant seq" = join seq ==> id
 warn "Redundant $!" = id $! x ==> x
 warn "Redundant seq" = x `seq` y ==> y where _ = isWHNF x
 warn "Redundant $!" = f $! x ==> f x where _ = isWHNF x
@@ -399,7 +399,7 @@
 warn = Nothing /= x  ==>  Data.Maybe.isJust x
 warn = concatMap (maybeToList . f) ==> Data.Maybe.mapMaybe f
 warn = concatMap maybeToList ==> catMaybes
-warn = maybe n Just x ==> Control.Monad.mplus x n
+warn = maybe n Just x ==> x Control.Applicative.<|> n
 hint = (case x of Just a -> a; Nothing -> y)  ==> fromMaybe y x
 warn = (if isNothing x then y else fromJust x) ==> fromMaybe y x
 warn = (if isJust x then fromJust x else y) ==> fromMaybe y x
diff --git a/hlint.cabal b/hlint.cabal
--- a/hlint.cabal
+++ b/hlint.cabal
@@ -1,7 +1,7 @@
 cabal-version:      >= 1.8
 build-type:         Simple
 name:               hlint
-version:            1.9.32
+version:            1.9.33
 license:            BSD3
 license-file:       LICENSE
 category:           Development
diff --git a/src/HSE/Bracket.hs b/src/HSE/Bracket.hs
--- a/src/HSE/Bracket.hs
+++ b/src/HSE/Bracket.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE PatternGuards, TypeSynonymInstances, FlexibleInstances #-}
+{-# OPTIONS_GHC -fno-warn-overlapping-patterns -fno-warn-incomplete-patterns #-}
 
 module HSE.Bracket(
     Brackets(..),
diff --git a/src/HSE/FreeVars.hs b/src/HSE/FreeVars.hs
--- a/src/HSE/FreeVars.hs
+++ b/src/HSE/FreeVars.hs
@@ -1,6 +1,6 @@
 {-# LANGUAGE FlexibleInstances, TypeSynonymInstances #-}
 
-module HSE.FreeVars(FreeVars, freeVars, vars, varss, pvars, declBind) where
+module HSE.FreeVars(FreeVars, freeVars, vars, varss, pvars) where
 
 import Data.Monoid
 import HSE.Type as HSE
@@ -8,10 +8,6 @@
 import Data.Set(Set)
 import Prelude
 
-
--- which names are bound by a declaration
-declBind :: Decl_ -> [String]
-declBind = pvars
 
 vars x = Set.toList $ freeVars x
 
diff --git a/src/HSE/Util.hs b/src/HSE/Util.hs
--- a/src/HSE/Util.hs
+++ b/src/HSE/Util.hs
@@ -263,9 +263,6 @@
           f (x:xs) = x : f xs
           f [] = []
 
-toSrcLoc :: SrcSpanInfo -> SrcLoc
-toSrcLoc = getPointLoc
-
 toSrcSpan :: SrcSpanInfo -> SrcSpan
 toSrcSpan (SrcSpanInfo x _) = x
 
diff --git a/src/Hint/All.hs b/src/Hint/All.hs
--- a/src/Hint/All.hs
+++ b/src/Hint/All.hs
@@ -1,14 +1,13 @@
 
 module Hint.All(
     Hint(..), HintBuiltin(..), DeclHint, ModuHint,
-    resolveHints, hintRules, resolveBuiltin, builtinHints
+    resolveHints, hintRules, builtinHints
     ) where
 
 import Data.Monoid
 import Settings
 import Data.Either
 import Data.List
-import Data.Maybe
 import Hint.Type
 import Prelude
 
@@ -67,10 +66,6 @@
 resolveHints :: [Either HintBuiltin HintRule] -> Hint
 resolveHints xs = mconcat $ mempty{hintDecl=readMatch rights} : map builtin (nub lefts)
     where (lefts,rights) = partitionEithers xs
-
-resolveBuiltin :: [String] -> [Hint]
-resolveBuiltin builtin = map f $ nub $ concat [if x == "All" then map fst builtinHints else [x] | x <- builtin]
-    where f x = fromMaybe (error $ "Unknown builtin hints: HLint.Builtin." ++ x) $ lookup x builtinHints
 
 hintRules :: [HintRule] -> Hint
 hintRules = resolveHints . map Right
diff --git a/src/Language/Haskell/HLint2.hs b/src/Language/Haskell/HLint2.hs
--- a/src/Language/Haskell/HLint2.hs
+++ b/src/Language/Haskell/HLint2.hs
@@ -38,6 +38,7 @@
 import Paths_hlint
 
 import Control.Applicative
+import Data.Maybe
 import Data.Monoid
 import Data.Tuple.Extra
 import Data.List.Extra
@@ -48,6 +49,11 @@
 -- | Get the Cabal configured data directory of HLint
 getHLintDataDir :: IO FilePath
 getHLintDataDir = getDataDir
+
+resolveBuiltin :: [String] -> [Hint]
+resolveBuiltin builtin = map f $ nub $ concat [if x == "All" then map fst builtinHints else [x] | x <- builtin]
+    where f x = fromMaybe (error $ "Unknown builtin hints: HLint.Builtin." ++ x) $ lookup x builtinHints
+
 
 -- | The function produces a tuple containg 'ParseFlags' (for 'parseModuleEx'), and 'Classify' and 'Hint' for 'applyHints'.
 --   It approximates the normal HLint configuration steps, roughly: