diff --git a/main.ml b/main.ml
index 33b7370..8c8c12a 100644
--- a/main.ml
+++ b/main.ml
@@ -6,6 +6,7 @@ let version = "%%VERSION%%"
 
 let error_to_string e =
   try raise e with
+  | Lex.Token_not_found -> sprintf "invalid token"
   | Parser.Expected t -> sprintf "expected %s" t
   | Parser.Unexpected_token t -> sprintf "unexpected token \"%s\"" t
   | Eval.Invalid_type -> "invalid type"