diff --git a/app/javascript/mastodon/compare_id.js b/app/javascript/mastodon/compare_id.js
new file mode 100644
index 00000000000..aaff66481ac
--- /dev/null
+++ b/app/javascript/mastodon/compare_id.js
@@ -0,0 +1,10 @@
+export default function compareId(id1, id2) {
+  if (id1 === id2) {
+    return 0;
+  }
+  if (id1.length === id2.length) {
+    return id1 > id2 ? 1 : -1;
+  } else {
+    return id1.length > id2.length ? 1 : -1;
+  }
+}
diff --git a/app/javascript/mastodon/reducers/notifications.js b/app/javascript/mastodon/reducers/notifications.js
index 1ac7eb706d1..da9b8c420ed 100644
--- a/app/javascript/mastodon/reducers/notifications.js
+++ b/app/javascript/mastodon/reducers/notifications.js
@@ -12,6 +12,7 @@ import {
 } from '../actions/accounts';
 import { TIMELINE_DELETE, TIMELINE_DISCONNECT } from '../actions/timelines';
 import { Map as ImmutableMap, List as ImmutableList } from 'immutable';
+import compareId from '../compare_id';
 
 const initialState = ImmutableMap({
   items: ImmutableList(),
@@ -44,13 +45,6 @@ const normalizeNotification = (state, notification) => {
   });
 };
 
-const newer = (m, n) => {
-  const mId = m.get('id');
-  const nId = n.get('id');
-
-  return mId.length === nId.length ? mId > nId : mId.length > nId.length;
-};
-
 const expandNormalizedNotifications = (state, notifications, next) => {
   let items = ImmutableList();
 
@@ -62,11 +56,11 @@ const expandNormalizedNotifications = (state, notifications, next) => {
     if (!items.isEmpty()) {
       mutable.update('items', list => {
         const lastIndex = 1 + list.findLastIndex(
-          item => item !== null && (newer(item, items.last()) || item.get('id') === items.last().get('id'))
+          item => item !== null && (compareId(item.get('id'), items.last().get('id')) > 0 || item.get('id') === items.last().get('id'))
         );
 
         const firstIndex = 1 + list.take(lastIndex).findLastIndex(
-          item => item !== null && newer(item, items.first())
+          item => item !== null && compareId(item.get('id'), items.first().get('id')) > 0
         );
 
         return list.take(firstIndex).concat(items, list.skip(lastIndex));
diff --git a/app/javascript/mastodon/reducers/timelines.js b/app/javascript/mastodon/reducers/timelines.js
index f795e7e0891..ad897bcc979 100644
--- a/app/javascript/mastodon/reducers/timelines.js
+++ b/app/javascript/mastodon/reducers/timelines.js
@@ -13,6 +13,7 @@ import {
   ACCOUNT_UNFOLLOW_SUCCESS,
 } from '../actions/accounts';
 import { Map as ImmutableMap, List as ImmutableList, fromJS } from 'immutable';
+import compareId from '../compare_id';
 
 const initialState = ImmutableMap();
 
@@ -32,8 +33,8 @@ const expandNormalizedTimeline = (state, timeline, statuses, next, isPartial) =>
     if (!statuses.isEmpty()) {
       mMap.update('items', ImmutableList(), oldIds => {
         const newIds = statuses.map(status => status.get('id'));
-        const lastIndex = oldIds.findLastIndex(id => id !== null && id >= newIds.last()) + 1;
-        const firstIndex = oldIds.take(lastIndex).findLastIndex(id => id !== null && id > newIds.first());
+        const lastIndex = oldIds.findLastIndex(id => id !== null && compareId(id, newIds.last()) >= 0) + 1;
+        const firstIndex = oldIds.take(lastIndex).findLastIndex(id => id !== null && compareId(id, newIds.first()) >= 0);
 
         if (firstIndex < 0) {
           return (isPartial ? newIds.unshift(null) : newIds).concat(oldIds.skip(lastIndex));