diff --git a/changelog/unreleased/enhancement-replace-deprecated-substr b/changelog/unreleased/enhancement-replace-deprecated-substr
new file mode 100644
index 000000000..4fdbddf5c
--- /dev/null
+++ b/changelog/unreleased/enhancement-replace-deprecated-substr
@@ -0,0 +1,7 @@
+Enhancement: Replace deprecated String.prototype.substr()
+
+We've replaced all occurrences of the deprecated String.prototype.substr()
+function with String.prototype.slice() which works similarly but isn't
+deprecated.
+
+https://github.com/owncloud/ocis/pull/3448
diff --git a/idp/ui/src/containers/Login/Chooseaccount.js b/idp/ui/src/containers/Login/Chooseaccount.js
index 5eba58f4f..fd40b7ab6 100644
--- a/idp/ui/src/containers/Login/Chooseaccount.js
+++ b/idp/ui/src/containers/Login/Chooseaccount.js
@@ -85,7 +85,7 @@ function Chooseaccount({ loading, errors, classes, hello, history, dispatch }) {
             className={classes.accountListItem}
             disabled={!!loading}
             onClick={(event) => logon(event)}
-          ><ListItemAvatar><Avatar>{username.substr(0, 1)}</Avatar></ListItemAvatar>
+          ><ListItemAvatar><Avatar>{username.slice(0, 1)}</Avatar></ListItemAvatar>
             <ListItemText className="oc-light" primary={username} />
           </ListItem>
           <ListItem
diff --git a/idp/ui_config/paths.js b/idp/ui_config/paths.js
index 7d2cce9b0..88d482970 100644
--- a/idp/ui_config/paths.js
+++ b/idp/ui_config/paths.js
@@ -14,7 +14,7 @@ const envPublicUrl = process.env.PUBLIC_URL;
 function ensureSlash(inputPath, needsSlash) {
   const hasSlash = inputPath.endsWith('/');
   if (hasSlash && !needsSlash) {
-    return inputPath.substr(0, inputPath.length - 1);
+    return inputPath.slice(0, -1);
   } else if (!hasSlash && needsSlash) {
     return `${inputPath}/`;
   } else {
diff --git a/settings/ui/components/SettingsBundle.vue b/settings/ui/components/SettingsBundle.vue
index c62d22bf6..40d439462 100644
--- a/settings/ui/components/SettingsBundle.vue
+++ b/settings/ui/components/SettingsBundle.vue
@@ -49,7 +49,7 @@ export default {
   methods: {
     ...mapActions('Settings', ['saveValue']),
     getSettingComponent (setting) {
-      return 'Setting' + setting.type[0].toUpperCase() + setting.type.substr(1)
+      return 'Setting' + setting.type[0].toUpperCase() + setting.type.slice(1)
     },
     getValue (setting) {
       return this.getSettingsValue({ settingId: setting.id })