diff --git a/app/javascript/flavours/glitch/features/status/components/card.js b/app/javascript/flavours/glitch/features/status/components/card.js
index 14abe9838ba..0ca2508e710 100644
--- a/app/javascript/flavours/glitch/features/status/components/card.js
+++ b/app/javascript/flavours/glitch/features/status/components/card.js
@@ -24,7 +24,7 @@ const trim = (text, len) => {
     return text;
   }
 
-  return text.substring(0, cut) + (text.length > len ? '…' : '');
+  return text.slice(0, cut) + (text.length > len ? '…' : '');
 };
 
 const domParser = new DOMParser();
diff --git a/app/javascript/flavours/glitch/features/video/index.js b/app/javascript/flavours/glitch/features/video/index.js
index 53e3dfda382..25c94bb2c51 100644
--- a/app/javascript/flavours/glitch/features/video/index.js
+++ b/app/javascript/flavours/glitch/features/video/index.js
@@ -90,7 +90,7 @@ export const fileNameFromURL = str => {
   const pathname = url.pathname;
   const index    = pathname.lastIndexOf('/');
 
-  return pathname.substring(index + 1);
+  return pathname.slice(index + 1);
 };
 
 export default @injectIntl
diff --git a/app/javascript/flavours/glitch/util/emoji/emoji_mart_search_light.js b/app/javascript/flavours/glitch/util/emoji/emoji_mart_search_light.js
index e4519a13e62..70694ab6dde 100644
--- a/app/javascript/flavours/glitch/util/emoji/emoji_mart_search_light.js
+++ b/app/javascript/flavours/glitch/util/emoji/emoji_mart_search_light.js
@@ -124,7 +124,7 @@ function search(value, { emojisToShowFilter, maxResults, include, exclude, custo
           for (let id in aPool) {
             let emoji = aPool[id],
               { search } = emoji,
-              sub = value.substr(0, length),
+              sub = value.slice(0, length),
               subIndex = search.indexOf(sub);
 
             if (subIndex !== -1) {