diff --git a/app/javascript/mastodon/reducers/compose.js b/app/javascript/mastodon/reducers/compose.js
index afb8b40c103f892fa0ee5bfe731f17794700052f..8cc7bf52057f67d99ee18163b67605c75c2f62d9 100644
--- a/app/javascript/mastodon/reducers/compose.js
+++ b/app/javascript/mastodon/reducers/compose.js
@@ -436,7 +436,7 @@ export default function compose(state = initialState, action) {
       .setIn(['media_modal', 'dirty'], false)
       .update('media_attachments', list => list.map(item => {
         if (item.get('id') === action.media.id) {
-          return fromJS(action.media);
+          return fromJS(action.media).set('unattached', true);
         }
 
         return item;