diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index 22eda7e24b..b8d233ca13 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -171,6 +171,7 @@
 		<li>[Fix] Preserve newlines in template files (one newline had been always dropped after a template variable due to PHP's handling of closing tags)</li>
 		<li>[Fix] Be less strict with FTP daemons when getting directory filelists. (Bug #46295)</li>
 		<li>[Fix] Fix set_custom_template for database-stored styles (Bug #40515 - Patch by nickvergessen)</li>
+		<li>[Fix] Banning an already banned user states to be successful, but has no effect (Bug #47825 - Patch by Pyramide)</li>
 		<li>[Change] Change the data format of the default file ACM to be more secure from tampering and have better performance.</li>
 		<li>[Change] Add index on log_time to the log table to prevent slowdown on boards with many log entries. (Bug #44665 - Patch by bantu)</li>
 		<li>[Change] Template engine now permits to a limited extent variable includes.</li>
diff --git a/phpBB/includes/functions_user.php b/phpBB/includes/functions_user.php
index c69c27c9d7..e8584239ad 100644
--- a/phpBB/includes/functions_user.php
+++ b/phpBB/includes/functions_user.php
@@ -1016,7 +1016,17 @@ function user_ban($mode, $ban, $ban_len, $ban_len_other, $ban_exclude, $ban_reas
 		}
 		while ($row = $db->sql_fetchrow($result));
 
-		$banlist_ary = array_unique(array_diff($banlist_ary, $banlist_ary_tmp));
+		$banlist_ary_tmp = array_intersect($banlist_ary, $banlist_ary_tmp);
+
+		if (sizeof($banlist_ary_tmp))
+		{
+			// One or more entities are already banned/excluded, delete the existing bans, so they can be re-inserted with the given new length
+			$sql = 'DELETE FROM ' . BANLIST_TABLE . '
+				WHERE ' . $db->sql_in_set($type, $banlist_ary_tmp) . '
+					AND ban_exclude = ' . (int) $ban_exclude;
+			$db->sql_query($sql);
+		}
+
 		unset($banlist_ary_tmp);
 	}
 	$db->sql_freeresult($result);