diff --git a/src/glob.ml b/src/glob.ml
index 3eb6326..7bd75a8 100644
--- a/src/glob.ml
+++ b/src/glob.ml
@@ -159,15 +159,31 @@ let of_string ?(dir_sep = default_dir_sep) s =
     let cs = char_class_of_chars cs in
     (cs, idx)
   in
-  let components = normal [] 0 in
-  Ok { dir_sep; components }
+  match normal [] 0 with
+  | components -> Ok { dir_sep; components }
+  | exception Failure msg -> Error msg
 
 let to_string t =
   let buf = Buffer.create 16 in
+  let add_literal_string s =
+    String.iter
+      (fun c ->
+        match c with
+        | '*' | '?' | '[' ->
+            Buffer.add_char buf '[';
+            Buffer.add_char buf c;
+            Buffer.add_char buf ']'
+        | c when Char.equal c t.dir_sep ->
+            Buffer.add_char buf '[';
+            Buffer.add_char buf c;
+            Buffer.add_char buf ']'
+        | c -> Buffer.add_char buf c)
+      s
+  in
   List.iter
     (function
       | Dir_sep -> Buffer.add_char buf t.dir_sep
-      | String s -> Buffer.add_string buf s
+      | String s -> add_literal_string s
       | Question -> Buffer.add_char buf '?'
       | Star -> Buffer.add_char buf '*'
       | Range cs ->