diff --git a/shh.cabal b/shh.cabal
--- a/shh.cabal
+++ b/shh.cabal
@@ -1,5 +1,5 @@
 name:                shh
-version:             0.3.1.2
+version:             0.3.1.3
 synopsis:            Simple shell scripting from Haskell
 description:         Provides a shell scripting environment for Haskell. It
                      helps you all external binaries, and allows you to
diff --git a/src/Shh/Internal.hs b/src/Shh/Internal.hs
--- a/src/Shh/Internal.hs
+++ b/src/Shh/Internal.hs
@@ -400,13 +400,18 @@
     pathsVar <- splitOn ":" <$> getEnv "PATH"
     paths <- filterM Dir.doesDirectoryExist pathsVar
     ps <- ordNubOn takeFileName . concat <$> mapM (\d -> fmap (\x -> d++('/':x)) <$> Dir.getDirectoryContents d) paths
-    filterM (fmap Dir.executable . Dir.getPermissions) ps
+    filterM (tryBool . fmap Dir.executable . Dir.getPermissions) ps
 
     where
         -- TODO: Eventually replace this with nubOrdOn (containers 0.6.0.1 dep)
         ordNubOn :: Ord b => (a -> b) -> [a] -> [a]
         ordNubOn f as = map snd . Map.toList . Map.fromListWith const $ zip (map f as) as
 
+        tryBool :: IO Bool -> IO Bool
+        tryBool a = try a >>= \case
+            Left (SomeException _) -> pure False
+            Right r -> pure r
+
 -- | Execute the given command. Further arguments can be passed in.
 --
 -- > exe "ls" "-l"
@@ -459,6 +464,8 @@
 -- is some chance of overlap. If the string is a path, the filename portion
 -- is used. The transformation replaces all non-alphanumeric characters
 -- with @'_'@. If the first character is uppercase it is forced into lowercase.
+-- If it starts with a number, it is prefixed with `_`. If it overlaps with
+-- a reserved word or a builtin, it is suffixed with an `_`.
 encodeIdentifier :: String -> String
 encodeIdentifier ident =
     let