diff --git a/tools/delete-stray-images.php b/tools/delete-stray-images.php
new file mode 100644
index 00000000..cf0dff46
--- /dev/null
+++ b/tools/delete-stray-images.php
@@ -0,0 +1,61 @@
+#!/usr/bin/php
+<?php
+/*
+ *  delete-stray-images.php - there was a period when undoImage() was not working at all. This meant that
+ *  if an error occured while uploading an image, the uploaded images might not have been deleted.
+ *
+ *  This script iterates through every board and deletes any stray files in src/ or thumb/ that don't
+ *  exist in the database.
+ *
+ */
+
+require dirname(__FILE__) . '/inc/cli.php';
+
+
+$boards = listBoards();
+
+foreach ($boards as $board) {
+	echo "/{$board['uri']}/... ";
+	
+	openBoard($board['uri']);
+	
+	$query = query(sprintf("SELECT `file`, `thumb` FROM ``posts_%s`` WHERE `file` IS NOT NULL", $board['uri']));
+	$valid_src = array();
+	$valid_thumb = array();
+	
+	while ($post = $query->fetch(PDO::FETCH_ASSOC)) {
+		$valid_src[] = $post['file'];
+		$valid_thumb[] = $post['thumb'];
+	}
+	
+	$files_src = array_map('basename', glob($board['dir'] . $config['dir']['img'] . '*'));
+	$files_thumb = array_map('basename', glob($board['dir'] . $config['dir']['thumb'] . '*'));
+	
+	$stray_src = array_diff($files_src, $valid_src);
+	$stray_thumb = array_diff($files_thumb, $valid_thumb);
+	
+	$stats = array(
+		'deleted' => 0,
+		'size' => 0
+	);
+	
+	foreach ($stray_src as $src) {
+		$stats['deleted']++;
+		$stats['size'] = filesize($board['dir'] . $config['dir']['img'] . $src);
+		if (!file_unlink($board['dir'] . $config['dir']['img'] . $src)) {
+			$er = error_get_last();
+			die("error: " . $er['message'] . "\n");
+		}
+	}
+		
+	foreach ($stray_src as $thumb) {
+		$stats['deleted']++;
+		$stats['size'] = filesize($board['dir'] . $config['dir']['thumb'] . $thumb);
+		if (!file_unlink($board['dir'] . $config['dir']['thumb'] . $src)) {
+			$er = error_get_last();
+			die("error: " . $er['message'] . "\n");
+		}
+	}
+	
+	echo sprintf("deleted %s files (%s)\n", $stats['deleted'], format_bytes($stats['size']));
+}