From b21ab498f84b75288f20a7eb2c6e0ee223481674 Mon Sep 17 00:00:00 2001
From: Naoki Kosaka <n.k@mail.yukimochi.net>
Date: Wed, 12 Jul 2017 02:56:45 +0900
Subject: [PATCH] Fix media modal prev button behavior. (#4158)

---
 app/javascript/mastodon/features/ui/components/media_modal.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/app/javascript/mastodon/features/ui/components/media_modal.js b/app/javascript/mastodon/features/ui/components/media_modal.js
index 23f588669f..d869fffa67 100644
--- a/app/javascript/mastodon/features/ui/components/media_modal.js
+++ b/app/javascript/mastodon/features/ui/components/media_modal.js
@@ -35,7 +35,7 @@ export default class MediaModal extends ImmutablePureComponent {
   }
 
   handlePrevClick = () => {
-    this.setState({ index: (this.getIndex() - 1) % this.props.media.size });
+    this.setState({ index: (this.props.media.size + this.getIndex() - 1) % this.props.media.size });
   }
 
   handleKeyUp = (e) => {