1 files changed, 1 insertions, 1 deletions

diff --git a/fsmgr.hs b/fsmgr.hs
index b1469ba..1f5af37 100644
--- a/fsmgr.hs
+++ b/fsmgr.hs
@@ -56,7 +56,7 @@ buildRoot :: DiskImageConfig -> FilePath -> Action ()
 buildRoot config@DiskImageConfig{..} finalOut = do
   let out        = finalOut <.> "tmp"
       mountpoint = finalOut <.> "mnt"
-  cmd_ "sh -c" ["! mountpoint -q \"$0\" || umount \"$0\" ", mountpoint]
+  cmd_ "sh -c" ["if mountpoint -q \"$0\"; then umount \"$0\"; fi", mountpoint]
 
   let (abortion :: IO ()) = ignoreErrors' $ do
         cmd_ "umount" [mountpoint]