diff --git a/shake-ext.cabal b/shake-ext.cabal
--- a/shake-ext.cabal
+++ b/shake-ext.cabal
@@ -1,12 +1,13 @@
 cabal-version: 1.18
 name: shake-ext
-version: 3.0.0.0
+version: 3.0.1.0
 license: BSD3
 license-file: LICENSE
 copyright: Copyright: (c) 2018 Vanessa McHale
 maintainer: vamchale@gmail.com
 author: Vanessa McHale
 homepage: https://hub.darcs.net/vmchale/shake-ext
+bug-reports: https://hub.darcs.net/vmchale/ats/issues
 synopsis: Helper functions for linting with shake
 description:
     This package provides several linters out of the box, for use with [shake](http://shakebuild.com/).
diff --git a/src/Development/Shake/FileDetect.hs b/src/Development/Shake/FileDetect.hs
--- a/src/Development/Shake/FileDetect.hs
+++ b/src/Development/Shake/FileDetect.hs
@@ -14,9 +14,10 @@
     , getDhall
     , getElm
     , getMadlang
+    , getC
     ) where
 
-import           Control.Monad
+import           Data.Foldable     (fold)
 import           Data.Semigroup    ((<>))
 import           Development.Shake
 
@@ -24,6 +25,9 @@
 getMadlang :: Action [FilePath]
 getMadlang = getAll ["mad"]
 
+getC :: Action [FilePath]
+getC = getAll ["c"]
+
 getElm :: Action [FilePath]
 getElm = getAll ["elm"]
 
@@ -38,7 +42,7 @@
 
 -- | Get all haskell source files, including module signatures.
 getHs :: [FilePath] -> Action [FilePath]
-getHs files = join <$> mapM (`getAllDir` ["hs", "hs-boot", "hsig", "lhs"]) files
+getHs files = fold <$> traverse (`getAllDir` ["hs", "hs-boot", "hsig", "lhs"]) files
 
 getHappy :: Action [FilePath]
 getHappy = getAll ["y", "yl"]
diff --git a/src/Development/Shake/Linters.hs b/src/Development/Shake/Linters.hs
--- a/src/Development/Shake/Linters.hs
+++ b/src/Development/Shake/Linters.hs
@@ -11,18 +11,19 @@
                                  , clangFormat
                                  , atsfmt
                                  , stylishHaskell
+                                 , cFormat
                                  -- * File detection
                                  , module Development.Shake.FileDetect
                                  ) where
 
-import           Control.Monad
 import           Data.Char                    (isSpace)
+import           Data.Foldable                (traverse_)
 import           Development.Shake
 import           Development.Shake.FileDetect
 
 -- | Check all @.dhall@ files.
 dhall :: Action ()
-dhall = mapM_ checkDhall =<< getDhall
+dhall = traverse_ checkDhall =<< getDhall
 
 checkDhall :: FilePath -> Action ()
 checkDhall dh = do
@@ -30,7 +31,7 @@
     command [Stdin contents] "dhall" []
 
 trim :: String -> String
-trim = join fmap f
+trim = f . f
    where f = reverse . dropWhile isSpace
 
 -- | Check a given formatter is idempotent.
@@ -42,18 +43,22 @@
 
 -- | Check that given files are formatted according to @stylish-haskell@
 stylishHaskell :: [FilePath] -> Action ()
-stylishHaskell = mapM_ (checkIdempotent "stylish-haskell")
+stylishHaskell = traverse_ (checkIdempotent "stylish-haskell")
 
 -- | Check that given files are formatted according to @atsfmt@
 atsfmt :: [FilePath] -> Action ()
-atsfmt = mapM_ (checkIdempotent "atsfmt")
+atsfmt = traverse_ (checkIdempotent "atsfmt")
 
 -- | Check that given files are formatted according to @clang-format@
 clangFormat :: [FilePath] -> Action ()
-clangFormat = mapM_ (checkIdempotent "clang-format")
+clangFormat = traverse_ (checkIdempotent "clang-format")
 
+-- | Check all @.c@ files using @clang-format@.
+cFormat :: Action ()
+cFormat = clangFormat =<< getC
+
 checkFiles :: String -> [FilePath] -> Action ()
-checkFiles str = mapM_ (cmd_ . ((str ++ " ") ++))
+checkFiles str = traverse_ (cmd_ . ((str ++ " ") ++))
 
 -- | Check all @.mad@ files.
 madlang :: [FilePath] -> Action ()