diff --git a/app/javascript/mastodon/features/compose/components/compose_form.js b/app/javascript/mastodon/features/compose/components/compose_form.js
index 0625ab223..ac458fd25 100644
--- a/app/javascript/mastodon/features/compose/components/compose_form.js
+++ b/app/javascript/mastodon/features/compose/components/compose_form.js
@@ -46,6 +46,7 @@ class ComposeForm extends ImmutablePureComponent {
     caretPosition: PropTypes.number,
     preselectDate: PropTypes.instanceOf(Date),
     is_submitting: PropTypes.bool,
+    is_changing_upload: PropTypes.bool,
     is_uploading: PropTypes.bool,
     onChange: PropTypes.func.isRequired,
     onSubmit: PropTypes.func.isRequired,
@@ -81,10 +82,10 @@ class ComposeForm extends ImmutablePureComponent {
     }
 
     // Submit disabled:
-    const { is_submitting, is_uploading, anyMedia } = this.props;
+    const { is_submitting, is_changing_upload, is_uploading, anyMedia } = this.props;
     const fulltext = [this.props.spoiler_text, countableText(this.props.text)].join('');
 
-    if (is_submitting || is_uploading || length(fulltext) > 500 || (fulltext.length !== 0 && fulltext.trim().length === 0 && !anyMedia)) {
+    if (is_submitting || is_uploading || is_changing_upload || length(fulltext) > 500 || (fulltext.length !== 0 && fulltext.trim().length === 0 && !anyMedia)) {
       return;
     }
 
@@ -160,7 +161,7 @@ class ComposeForm extends ImmutablePureComponent {
     const { intl, onPaste, showSearch, anyMedia } = this.props;
     const disabled = this.props.is_submitting;
     const text     = [this.props.spoiler_text, countableText(this.props.text)].join('');
-    const disabledButton = disabled || this.props.is_uploading || length(text) > 500 || (text.length !== 0 && text.trim().length === 0 && !anyMedia);
+    const disabledButton = disabled || this.props.is_uploading || this.props.is_changing_upload || length(text) > 500 || (text.length !== 0 && text.trim().length === 0 && !anyMedia);
     let publishText = '';
 
     if (this.props.privacy === 'private' || this.props.privacy === 'direct') {
diff --git a/app/javascript/mastodon/features/compose/containers/compose_form_container.js b/app/javascript/mastodon/features/compose/containers/compose_form_container.js
index 5d7fb8852..b4a1c4b44 100644
--- a/app/javascript/mastodon/features/compose/containers/compose_form_container.js
+++ b/app/javascript/mastodon/features/compose/containers/compose_form_container.js
@@ -22,6 +22,7 @@ const mapStateToProps = state => ({
   caretPosition: state.getIn(['compose', 'caretPosition']),
   preselectDate: state.getIn(['compose', 'preselectDate']),
   is_submitting: state.getIn(['compose', 'is_submitting']),
+  is_changing_upload: state.getIn(['compose', 'is_changing_upload']),
   is_uploading: state.getIn(['compose', 'is_uploading']),
   showSearch: state.getIn(['search', 'submitted']) && !state.getIn(['search', 'hidden']),
   anyMedia: state.getIn(['compose', 'media_attachments']).size > 0,
diff --git a/app/javascript/mastodon/reducers/compose.js b/app/javascript/mastodon/reducers/compose.js
index 67d55f66f..1622871b8 100644
--- a/app/javascript/mastodon/reducers/compose.js
+++ b/app/javascript/mastodon/reducers/compose.js
@@ -51,6 +51,7 @@ const initialState = ImmutableMap({
   in_reply_to: null,
   is_composing: false,
   is_submitting: false,
+  is_changing_upload: false,
   is_uploading: false,
   progress: 0,
   media_attachments: ImmutableList(),
@@ -79,6 +80,7 @@ function clearAll(state) {
     map.set('spoiler', false);
     map.set('spoiler_text', '');
     map.set('is_submitting', false);
+    map.set('is_changing_upload', false);
     map.set('in_reply_to', null);
     map.set('privacy', state.get('default_privacy'));
     map.set('sensitive', false);
@@ -248,13 +250,15 @@ export default function compose(state = initialState, action) {
       map.set('idempotencyKey', uuid());
     });
   case COMPOSE_SUBMIT_REQUEST:
-  case COMPOSE_UPLOAD_CHANGE_REQUEST:
     return state.set('is_submitting', true);
+  case COMPOSE_UPLOAD_CHANGE_REQUEST:
+    return state.set('is_changing_upload', true);
   case COMPOSE_SUBMIT_SUCCESS:
     return clearAll(state);
   case COMPOSE_SUBMIT_FAIL:
-  case COMPOSE_UPLOAD_CHANGE_FAIL:
     return state.set('is_submitting', false);
+  case COMPOSE_UPLOAD_CHANGE_FAIL:
+    return state.set('is_changing_upload', false);
   case COMPOSE_UPLOAD_REQUEST:
     return state.set('is_uploading', true);
   case COMPOSE_UPLOAD_SUCCESS:
@@ -300,7 +304,7 @@ export default function compose(state = initialState, action) {
     return insertEmoji(state, action.position, action.emoji, action.needsSpace);
   case COMPOSE_UPLOAD_CHANGE_SUCCESS:
     return state
-      .set('is_submitting', false)
+      .set('is_changing_upload', false)
       .update('media_attachments', list => list.map(item => {
         if (item.get('id') === action.media.id) {
           return fromJS(action.media);