diff --git a/shared.php b/shared.php
index ee87b4d..f1be203 100644
--- a/shared.php
+++ b/shared.php
@@ -54,7 +54,7 @@
 	 *            treated as an absolute path and no downscaled preview will be rendered.
 	 *            Other paths will be prefixed with /b/img.
 	 * $preview : When set to "", no preview will be generated. Otherwise the specified
-	 *            path will be used.
+	 *            path will be used. Use "+" to auto-generate.
 	 * $link    : Link to follow when clicking the image. Default is the full resolution image.
 	 */
 	$counters['figure'] = 1;