diff --git a/Static-filter-syntax.md b/Static-filter-syntax.md
index e7a552a..6a9b670 100644
--- a/Static-filter-syntax.md
+++ b/Static-filter-syntax.md
@@ -788,6 +788,8 @@ See also [`denyallow`](#denyallow)
 
 #### `empty`
 
+Deprecated, avoid using this option. See [deprecation notice from AdGuard](https://adguard.com/kb/general/ad-filtering/create-own-filters/#empty-modifier).
+
 New in [1.22.0](https://github.com/gorhill/uBlock/commit/3e5c9e00ab3603ae0c02e08b007b084404bbb71d).
 
 Redirects request to empty response.
@@ -800,6 +802,8 @@ See also: [`mp4`](#mp4), [`redirect`](#redirect)
 
 #### `mp4`
 
+Deprecated, avoid using this option. See [deprecation notice from AdGuard](https://adguard.com/kb/general/ad-filtering/create-own-filters/#mp4-modifier).
+
 New in [1.22.0](https://github.com/gorhill/uBlock/commit/68ae847ba385c09c5efa511d18a18a4753af47be).
 
 The `mp4` filter option will be converted to `redirect=noopmp4-1s` internally, and the `media` type is assumed.