diff --git a/apps/packages/infrastructure/src/auth/jwt.ts b/apps/packages/infrastructure/src/auth/jwt.ts
index 4be1aa1..8110441 100644
--- a/apps/packages/infrastructure/src/auth/jwt.ts
+++ b/apps/packages/infrastructure/src/auth/jwt.ts
@@ -29,7 +29,8 @@ const ACCESS_TOKEN_EXPIRY_SECS = 3600; // 1 hour
 const REFRESH_TOKEN_EXPIRY_SECS = 604800; // 7 days
 
 function base64url(data: string | Buffer): string {
-  const str = typeof data === "string" ? data : data.toString("base64");
+  const str =
+    typeof data === "string" ? Buffer.from(data, "utf8").toString("base64") : data.toString("base64");
   return str.replace(/\+/g, "-").replace(/\//g, "_").replace(/=+$/, "");
 }