diff --git a/server/routes/app.ts b/server/routes/app.ts
index 6731dcc6d..3c0266fb5 100644
--- a/server/routes/app.ts
+++ b/server/routes/app.ts
@@ -6,6 +6,7 @@ import escape from "lodash/escape";
import { Sequelize } from "sequelize";
import isUUID from "validator/lib/isUUID";
import { IntegrationType, TeamPreference } from "@shared/types";
+import { unicodeCLDRtoISO639 } from "@shared/utils/date";
import documentLoader from "@server/commands/documentLoader";
import env from "@server/env";
import { Integration } from "@server/models";
@@ -91,6 +92,7 @@ export const renderApp = async (
ctx.body = page
.toString()
.replace(/\{env\}/g, environment)
+ .replace(/\{lang\}/g, unicodeCLDRtoISO639(env.DEFAULT_LANGUAGE))
.replace(/\{title\}/g, escape(title))
.replace(/\{description\}/g, escape(description))
.replace(/\{canonical-url\}/g, canonical)
diff --git a/server/static/index.html b/server/static/index.html
index 73cf7c9c5..2b6ec8dc0 100644
--- a/server/static/index.html
+++ b/server/static/index.html
@@ -1,5 +1,5 @@
-
+
{title}
diff --git a/shared/utils/date.ts b/shared/utils/date.ts
index 9dad4cd69..dcd9ed1eb 100644
--- a/shared/utils/date.ts
+++ b/shared/utils/date.ts
@@ -106,6 +106,16 @@ export function unicodeBCP47toCLDR(locale: string) {
return locale.replace("-", "_").replace("und", "root");
}
+/**
+ * Converts a locale string from Unicode CLDR format to ISO 639 format.
+ *
+ * @param locale The locale string to convert
+ * @returns The converted locale string
+ */
+export function unicodeCLDRtoISO639(locale: string) {
+ return locale.split("_")[0];
+}
+
/**
* Returns the current date as a string formatted depending on current locale.
*