diff --git a/hlint.cabal b/hlint.cabal
--- a/hlint.cabal
+++ b/hlint.cabal
@@ -1,7 +1,7 @@
 cabal-version:      >= 1.6
 build-type:         Simple
 name:               hlint
-version:            1.6.6
+version:            1.6.7
 license:            GPL
 license-file:       LICENSE
 category:           Development
@@ -23,16 +23,21 @@
     report.html
     hs-lint.el
     hlint.1
-Extra-Source-Files:
+extra-source-files:
     hlint.htm
 
+flag threaded
+    default: True
+    description: Build with support for multithreaded execution
 
 executable hlint
     build-depends:
         base == 4.*, syb, filepath, directory, mtl, containers, hscolour >= 1.15, cpphs >= 1.7,
         haskell-src-exts == 1.1.*, uniplate == 1.2.* && >= 1.2.0.2
 
-    ghc-options:        -fno-warn-overlapping-patterns -threaded
+    ghc-options:        -fno-warn-overlapping-patterns
+    if flag(threaded)
+        ghc-options:    -threaded
 
     -- ViewPatterns not yet supported by Cabal as an extension
     -- extensions:         ViewPatterns, PatternGuards, MultiParamTypeClasses
diff --git a/src/Hint/Extensions.hs b/src/Hint/Extensions.hs
--- a/src/Hint/Extensions.hs
+++ b/src/Hint/Extensions.hs
@@ -26,15 +26,15 @@
 used RecursiveDo x = any isMDo $ universeBi x
 used ParallelListComp x = any isParComp $ universeBi x
 used FunctionalDependencies x = any isFunDep $ universeBi x
-used ImplicitParams x = not $ null (universeBi x :: [IPName])
+used ImplicitParams x = has x (undefined :: IPName)
 used EmptyDataDecls x = any f $ universeBi x
     where f (DataDecl _ _ _ _ _ [] _) = True
           f (GDataDecl _ _ _ _ _ _ [] _) = True
           f _ = False
-used KindSignatures x = not $ null (universeBi x :: [Kind])
+used KindSignatures x = has x (undefined :: Kind)
 used BangPatterns x = any isPBangPat $ universeBi x
-used TemplateHaskell x = not (null (universeBi x :: [Bracket])) && not (null (universeBi x :: [Splice]))
-used ForeignFunctionInterface x = not $ null (universeBi x :: [CallConv])
+used TemplateHaskell x = has x (undefined :: Bracket) || has x (undefined :: Splice)
+used ForeignFunctionInterface x = has x (undefined :: CallConv)
 used Generics x = any isPExplTypeArg $ universeBi x
 used PatternGuards x = any f $ universeBi x
     where f (GuardedRhs _ [] _) = False
@@ -54,8 +54,12 @@
           f RightArrApp{} = True
           f LeftArrHighApp{} = True
           f RightArrHighApp{} = True
+          f _ = False
 used TransformListComp x = any f $ universeBi x
     where f QualStmt{} = False
           f _ = True
 
 used _ _ = True
+
+
+has x t = not $ null (universeBi x `asTypeOf` [t])