diff --git a/src/sexp/CCSexp.ml b/src/sexp/CCSexp.ml
index bc83efa0..5934ab37 100644
--- a/src/sexp/CCSexp.ml
+++ b/src/sexp/CCSexp.ml
@@ -205,6 +205,7 @@ let parse_string s : t or_error =
 (*$T
   CCResult.to_opt (parse_string "(abc d/e/f \"hello \\\" () world\" )") <> None
   CCResult.to_opt (parse_string "(abc ( d e ffff   ) \"hello/world\")") <> None
+  CCResult.to_opt (parse_string "\"\123\bcoucou\"") <> None
 *)
 
 (*$inject
diff --git a/src/sexp/CCSexp_lex.mll b/src/sexp/CCSexp_lex.mll
index 4470a75b..c67e66eb 100644
--- a/src/sexp/CCSexp_lex.mll
+++ b/src/sexp/CCSexp_lex.mll
@@ -14,23 +14,39 @@
     let col = start.Lexing.pos_cnum - start.Lexing.pos_bol in
     raise (Error (line,col,msg))
 
+  type unescape_state =
+    | Not_escaped
+    | Escaped
+    | Escaped_int_1 of int
+    | Escaped_int_2 of int
+
   (* remove quotes + unescape *)
   let remove_quotes lexbuf s =
     assert (s.[0] = '"' && s.[String.length s - 1] = '"');
     let buf = Buffer.create (String.length s) in
-    let escaped = ref false in
+    let st = ref Not_escaped in
     for i = 1 to String.length s-2 do
-      match s.[i] with
-      | '\\' when !escaped -> Buffer.add_char buf '\\'; escaped := false
-      | '\\' -> escaped := true
-      | 'n' when !escaped -> Buffer.add_char buf '\n'; escaped := false
-      | 'r' when !escaped -> Buffer.add_char buf '\r'; escaped := false
-      | 't' when !escaped -> Buffer.add_char buf '\t'; escaped := false
-      | '"' when !escaped -> Buffer.add_char buf '"'; escaped := false
-      | c when !escaped -> error lexbuf (Printf.sprintf "wrong escape `%c`" c)
-      | c -> Buffer.add_char buf c;
+      match !st, s.[i] with
+      | Escaped, '\\' -> Buffer.add_char buf '\\'; st := Not_escaped
+      | Not_escaped, '\\' -> st := Escaped
+      | Escaped, 'n' -> Buffer.add_char buf '\n'; st := Not_escaped
+      | Escaped, 'r' -> Buffer.add_char buf '\r'; st := Not_escaped
+      | Escaped, 't' -> Buffer.add_char buf '\t'; st := Not_escaped
+      | Escaped, 'b' -> Buffer.add_char buf '\b'; st := Not_escaped
+      | Escaped, '"' -> Buffer.add_char buf '"'; st := Not_escaped
+      | Escaped, ('0'..'9' as c) ->
+          st := Escaped_int_1 (Char.code c - Char.code '0')
+      | Escaped_int_1 i, ('0'..'9' as c) ->
+          st := Escaped_int_2 (10*i+Char.code c - Char.code '0')
+      | Escaped_int_2 i, ('0'..'9' as c) ->
+          Buffer.add_char buf (Char.chr (10*i+Char.code c - Char.code '0'));
+          st := Not_escaped
+      | (Escaped | Escaped_int_1 _ | Escaped_int_2 _), c ->
+          error lexbuf (Printf.sprintf "wrong escape `%c`" c)
+      | Not_escaped, c -> Buffer.add_char buf c;
     done;
     Buffer.contents buf
+
 }
 
 let newline = '\n' | "\r\n"
@@ -40,7 +56,10 @@ let comment_line = ';' [^ '\n']*
 let printable_char = [^ '\n']
 
 let id = [^ ')' '(' '"' ' ' '\t' '\r' '\n']+
-let string = '"' ([^ '"' '\\'] | "\\\"" | "\\\\" | "\\n" | "\\t" | "\\r")* '"'
+let num = ['0'-'9']
+let string_item =
+  ([^ '"' '\\'] | "\\\"" | "\\\\" | "\\b" | "\\n" | "\\t" | "\\r" | '\\' num num num )
+let string = '"' string_item* '"'
 
 rule token = parse
   | comment_line { token lexbuf }