diff --git a/src/components/Support/Support.jsx b/src/components/Support/Support.jsx
index 4a0ce57b648a..0642933c6544 100644
--- a/src/components/Support/Support.jsx
+++ b/src/components/Support/Support.jsx
@@ -85,7 +85,7 @@ function formatMoney(number) {
   let str = Math.round(number) + '';
 
   if (str.length > 3) {
-    str = str.substr(0, str.length - 3) + ',' + str.substr(-3);
+    str = str.slice(0, -3) + ',' + str.slice(-3);
   }
   return str;
 }
diff --git a/src/remark-plugins/remark-custom-asides/index.mjs b/src/remark-plugins/remark-custom-asides/index.mjs
index e63990b0c6e9..96e7c43c808b 100644
--- a/src/remark-plugins/remark-custom-asides/index.mjs
+++ b/src/remark-plugins/remark-custom-asides/index.mjs
@@ -20,7 +20,7 @@ export default function customAsides(
       if (!textNode) return;
 
       // looking for mapping in the beginning
-      const className = mapping[textNode.substr(0, 2)];
+      const className = mapping[textNode.slice(0, 2)];
       // >This is a joke <- ignore this
       // >T hi there
       const hasPostfixWhitespace = textNode.indexOf(' ') === 2;