diff --git a/phpBB/includes/acp/acp_prune.php b/phpBB/includes/acp/acp_prune.php
index 1fd98af67f..5ffe45dc83 100644
--- a/phpBB/includes/acp/acp_prune.php
+++ b/phpBB/includes/acp/acp_prune.php
@@ -17,9 +17,10 @@ class acp_prune
 
 	function main($id, $mode)
 	{
-		global $user, $phpEx, $SID, $phpbb_admin_path;
+		global $user, $phpEx, $SID, $phpbb_admin_path, $phpbb_root_path;
 
 		$user->add_lang('acp/prune');
+		include_once($phpbb_root_path . 'includes/functions_user.' . $phpEx);
 
 		switch ($mode)
 		{
@@ -258,63 +259,48 @@ class acp_prune
 				$where_sql = '';
 				$user_ids = $usernames = array();
 
-				if ($row = $db->sql_fetchrow($result))
+				while ($row = $db->sql_fetchrow($result))
 				{
-					do
+					if (!in_array($row['user_id'], $bot_ids))
 					{
-						if (!in_array($row['user_id'], $bot_ids))
-						{
-							$where_sql .= (($where_sql != '') ? ', ' : '') . $row['user_id'];
-							$user_ids[] = $row['user_id'];
-							$usernames[] = $row['username'];
-						}
-					}
-					while ($row = $db->sql_fetchrow($result));
-
-					if ($where_sql)
-					{
-						$where_sql = " AND user_id IN ($where_sql)";
+						$user_ids[] = $row['user_id'];
+						$usernames[$row['user_id']] = $row['username'];
 					}
 				}
 				$db->sql_freeresult($result);
 
-				if ($where_sql)
+				if (sizeof($user_ids))
 				{
-					$sql = '';
+					if ($action == 'deactivate')
+					{
+						foreach ($user_ids as $user_id)
+						{
+							user_active_flip($user_id, USER_NORMAL, false, false, true);
+						}
 
-					if ($action == 'delete')
+						$l_log = 'LOG_PRUNE_USER_DEAC';
+					}
+					else if ($action == 'delete')
 					{
 						if ($deleteposts)
 						{
-							delete_posts('poster_id', $user_ids, true);
+							foreach ($user_ids as $user_id)
+							{
+								user_delete('remove', $user_id);
+							}
+							
 							$l_log = 'LOG_PRUNE_USER_DEL_DEL';
 						}
 						else
 						{
-							for ($i = 0, $size = sizeof($user_ids); $i < $size; $i++)
+							foreach ($user_ids as $user_id)
 							{
-								$sql = 'UPDATE ' . POSTS_TABLE . '
-									SET poster_id = ' . ANONYMOUS . ", post_username = '" . $db->sql_escape($usernames[$i]) . "'
-									WHERE user_id = " . $user_ids[$i];
-								$db->sql_query($sql);
+								user_delete('retain', $user_id, $usernames[$user_id]);
 							}
 
 							$l_log = 'LOG_PRUNE_USER_DEL_ANON';
 						}
-
-						$sql = 'DELETE FROM ' . USERS_TABLE;
 					}
-					else if ($action == 'deactivate')
-					{
-						$sql = 'UPDATE ' . USERS_TABLE . " 
-							SET user_active = 0";
-
-						$l_log = 'LOG_PRUNE_USER_DEAC';
-					}
-
-					$sql .= ' WHERE user_id <> ' . ANONYMOUS . "
-						$where_sql";
-					$db->sql_query($sql);
 
 					add_log('admin', $l_log, implode(', ', $usernames));
 				}
diff --git a/phpBB/includes/functions_user.php b/phpBB/includes/functions_user.php
index 3cf2c4ec4a..ecbdda032e 100644
--- a/phpBB/includes/functions_user.php
+++ b/phpBB/includes/functions_user.php
@@ -95,7 +95,7 @@ function user_update_name($old_name, $new_name)
 /**
 * Remove User
 */
-function user_delete($mode, $user_id)
+function user_delete($mode, $user_id, $post_username = false)
 {
 	global $config, $db, $user, $auth;
 
@@ -105,12 +105,12 @@ function user_delete($mode, $user_id)
 	{
 		case 'retain':
 			$sql = 'UPDATE ' . FORUMS_TABLE . '
-				SET forum_last_poster_id = ' . ANONYMOUS . "
+				SET forum_last_poster_id = ' . ANONYMOUS . (($post_username !== false) ? ", forum_last_poster_name = '" . $db->sql_escape($post_username) . "'" : '') . "
 				WHERE forum_last_poster_id = $user_id";
 			$db->sql_query($sql);
 
 			$sql = 'UPDATE ' . POSTS_TABLE . '
-				SET poster_id = ' . ANONYMOUS . "
+				SET poster_id = ' . ANONYMOUS . (($post_username !== false) ? ", post_username = '" . $db->sql_escape($post_username) . "'" : '') . "
 				WHERE poster_id = $user_id";
 			$db->sql_query($sql);
 
@@ -120,7 +120,7 @@ function user_delete($mode, $user_id)
 			$db->sql_query($sql);
 
 			$sql = 'UPDATE ' . TOPICS_TABLE . '
-				SET topic_last_poster_id = ' . ANONYMOUS . "
+				SET topic_last_poster_id = ' . ANONYMOUS . (($post_username !== false) ? ", topic_last_poster_name = '" . $db->sql_escape($post_username) . "'" : '') . "
 				WHERE topic_last_poster_id = $user_id";
 			$db->sql_query($sql);
 			break;
@@ -213,7 +213,7 @@ function user_delete($mode, $user_id)
 * Flips user_type from active to inactive and vice versa, handles
 * group membership updates
 */
-function user_active_flip($user_id, $user_type, $user_actkey = false, $username = false)
+function user_active_flip($user_id, $user_type, $user_actkey = false, $username = false, $no_log = false)
 {
 	global $db, $user, $auth;
 
@@ -274,18 +274,21 @@ function user_active_flip($user_id, $user_type, $user_actkey = false, $username
 
 	$auth->acl_clear_prefetch($user_id);
 
-	if ($username === false)
+	if (!$no_log)
 	{
-		$sql = 'SELECT username
-			FROM ' . USERS_TABLE . "
-			WHERE user_id = $user_id";
-		$result = $db->sql_query($sql);
-		$username = $db->sql_fetchfield('username', 0, $result);
-		$db->sql_freeresult($result);
-	}
+		if ($username === false)
+		{
+			$sql = 'SELECT username
+				FROM ' . USERS_TABLE . "
+				WHERE user_id = $user_id";
+			$result = $db->sql_query($sql);
+			$username = $db->sql_fetchfield('username', 0, $result);
+			$db->sql_freeresult($result);
+		}
 
-	$log = ($user_type == USER_NORMAL) ? 'LOG_USER_INACTIVE' : 'LOG_USER_ACTIVE';
-	add_log('admin', $log, $username);
+		$log = ($user_type == USER_NORMAL) ? 'LOG_USER_INACTIVE' : 'LOG_USER_ACTIVE';
+		add_log('admin', $log, $username);
+	}
 
 	return false;
 }