diff --git a/CHANGES.md b/CHANGES.md
index a4d80100dbc9fc033a140cfe34b84767132a5567..b2bf4eea21d515668948e8cd97727eaa58d3ccb5 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,6 +4,10 @@ moodle-auth_ldap_syncplus
 Changes
 -------
 
+### Unreleased
+
+* 2020-12-10 - Improvement: Declare which major stable version of Moodle this plugin supports (see MDL-59562 for details).
+
 ### v3.9-r1
 
 * 2020-09-18 - Prepare compatibility for Moodle 3.9.
diff --git a/version.php b/version.php
index a96d515b28af9220bdd8c8fca2e0f47b84071480..64a922cc01442dc345e6531a26eeedfc8a2b80bb 100644
--- a/version.php
+++ b/version.php
@@ -28,5 +28,6 @@ $plugin->component = 'auth_ldap_syncplus';
 $plugin->version = 2020091800;
 $plugin->release = 'v3.9-r1';
 $plugin->requires = 2020061500;
+$plugin->supported = [39, 39];
 $plugin->maturity = MATURITY_STABLE;
 $plugin->dependencies = array('auth_ldap' => 2020061500);