diff --git a/.eslintrc.js b/.eslintrc.js
index b6e4253e61dfff..93ff1d7b59030e 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -64,7 +64,6 @@ module.exports = defineConfig({
     'indent': ['error', 2],
     'jsx-quotes': ['error', 'prefer-single'],
     'semi': ['error', 'always'],
-    'no-case-declarations': 'off',
     'no-catch-shadow': 'error',
     'no-console': [
       'warn',
diff --git a/app/javascript/mastodon/actions/streaming.js b/app/javascript/mastodon/actions/streaming.js
index b6fc31fae855ac..30e643363a1c0d 100644
--- a/app/javascript/mastodon/actions/streaming.js
+++ b/app/javascript/mastodon/actions/streaming.js
@@ -106,12 +106,13 @@ export const connectTimelineStream = (timelineId, channelName, params = {}, opti
           dispatch(processNewNotificationForGroups(notificationJSON));
           break;
         }
-        case 'notifications_merged':
+        case 'notifications_merged': {
           const state = getState();
           if (state.notifications.top || !state.notifications.mounted)
             dispatch(expandNotifications({ forceLoad: true, maxId: undefined }));
           dispatch(refreshStaleNotificationGroups());
           break;
+        }
         case 'conversation':
           // @ts-expect-error
           dispatch(updateConversations(JSON.parse(data.payload)));
diff --git a/app/javascript/mastodon/reducers/compose.js b/app/javascript/mastodon/reducers/compose.js
index 9f66c09631d770..e77f2ac6e68904 100644
--- a/app/javascript/mastodon/reducers/compose.js
+++ b/app/javascript/mastodon/reducers/compose.js
@@ -407,7 +407,7 @@ export default function compose(state = initialState, action) {
 
         return item;
       }));
-  case INIT_MEDIA_EDIT_MODAL:
+  case INIT_MEDIA_EDIT_MODAL: {
     const media =  state.get('media_attachments').find(item => item.get('id') === action.id);
     return state.set('media_modal', ImmutableMap({
       id: action.id,
@@ -416,6 +416,7 @@ export default function compose(state = initialState, action) {
       focusY: media.getIn(['meta', 'focus', 'y'], 0),
       dirty: false,
     }));
+  }
   case COMPOSE_CHANGE_MEDIA_DESCRIPTION:
     return state.setIn(['media_modal', 'description'], action.description).setIn(['media_modal', 'dirty'], true);
   case COMPOSE_CHANGE_MEDIA_FOCUS:
diff --git a/app/javascript/mastodon/reducers/notifications.js b/app/javascript/mastodon/reducers/notifications.js
index 622f5e8e884bbd..c99a619b52dc69 100644
--- a/app/javascript/mastodon/reducers/notifications.js
+++ b/app/javascript/mastodon/reducers/notifications.js
@@ -298,9 +298,10 @@ export default function notifications(state = initialState, action) {
     return action.payload.timeline === 'home' ?
       state.update(action.payload.usePendingItems ? 'pendingItems' : 'items', items => items.first() ? items.unshift(null) : items) :
       state;
-  case NOTIFICATIONS_MARK_AS_READ:
+  case NOTIFICATIONS_MARK_AS_READ: {
     const lastNotification = state.get('items').find(item => item !== null);
     return lastNotification ? recountUnread(state, lastNotification.get('id')) : state;
+  }
   case NOTIFICATIONS_SET_BROWSER_SUPPORT:
     return state.set('browserSupport', action.value);
   case NOTIFICATIONS_SET_BROWSER_PERMISSION:
diff --git a/app/javascript/mastodon/reducers/search.js b/app/javascript/mastodon/reducers/search.js
index 7828d49eeedd9a..7de1c65c07a295 100644
--- a/app/javascript/mastodon/reducers/search.js
+++ b/app/javascript/mastodon/reducers/search.js
@@ -72,9 +72,10 @@ export default function search(state = initialState, action) {
     });
   case SEARCH_EXPAND_REQUEST:
     return state.set('type', action.searchType).set('isLoading', true);
-  case SEARCH_EXPAND_SUCCESS:
+  case SEARCH_EXPAND_SUCCESS: {
     const results = action.searchType === 'hashtags' ? ImmutableOrderedSet(fromJS(action.results.hashtags)) : action.results[action.searchType].map(item => item.id);
     return state.updateIn(['results', action.searchType], list => list.union(results)).set('isLoading', false);
+  }
   case SEARCH_HISTORY_UPDATE:
     return state.set('recent', ImmutableOrderedSet(fromJS(action.recent)));
   default: