diff --git a/repository/lib.php b/repository/lib.php
index 3f2e4ffeaad..978d4abebab 100644
--- a/repository/lib.php
+++ b/repository/lib.php
@@ -1789,9 +1789,12 @@ abstract class repository implements cacheable_object {
      *
      * @param string $source encoded and serialized data of file
      * @return int file size in bytes
+     *
+     * @deprecated since Moodle 4.3
      */
     public function get_file_size($source) {
-        // TODO MDL-33297 remove this function completely?
+        debugging(__FUNCTION__ . ' is deprecated, please do not use it any more', DEBUG_DEVELOPER);
+
         $browser    = get_file_browser();
         $params     = unserialize(base64_decode($source));
         $contextid  = clean_param($params['contextid'], PARAM_INT);
diff --git a/repository/upgrade.txt b/repository/upgrade.txt
index 19695c4bcb4..5b33b2c3d80 100644
--- a/repository/upgrade.txt
+++ b/repository/upgrade.txt
@@ -3,6 +3,9 @@ information provided here is intended especially for developers. Full
 details of the repository API are available on Moodle docs:
 http://docs.moodle.org/dev/Repository_API
 
+=== 4.3 ===
+* The base `repository` class method `get_file_size` has been deprecated and should not be used any more
+
 === 4.0 ===
 * The repository_boxnet has been completely removed.
 * The repository_picasa has been completely removed (Picasa is discontinued since 2016).