diff --git a/docs/customization.md b/docs/customization.md
index c6829b5da..3ba0bf6f3 100644
--- a/docs/customization.md
+++ b/docs/customization.md
@@ -175,7 +175,7 @@ commitizen:
 | `message`   | `str`  | `None`  | Detail description for the question.                                                                                                                                                            |
 | `choices`   | `list` | `None`  | (OPTIONAL) The choices when `type = list`. Either use a list of values or a list of dictionaries with `name` and `value` keys. Keyboard shortcuts can be defined via `key`. See examples above. |
 | `default`   | `Any`  | `None`  | (OPTIONAL) The default value for this question.                                                                                                                                                 |
-| `filter`    | `str`  | `None`  | (Optional) Validator for user's answer. **(Work in Progress)**                                                                                                                                  |
+| `filter`    | `str`  | `None`  | (OPTIONAL) Validator for user's answer. **(Work in Progress)**                                                                                                                                  |
 | `multiline` | `bool` | `False` | (OPTIONAL) Enable multiline support when `type = input`.                                                                                                                                            |
 [different-question-types]: https://github.com/tmbo/questionary#different-question-types