diff --git a/index.js b/index.js
index f367c7e..a687ade 100644
--- a/index.js
+++ b/index.js
@@ -5,7 +5,7 @@ const db = new sqlite3.Database('url.db');
 
 db.on('open', () => {
 	db.run('CREATE TABLE IF NOT EXISTS urls (shortUrl TEXT, url TEXT, visits INTEGER DEFAULT 0)');
-	db.run('CREATE TABLE IF NOT EXISTS refs (shortUrl TEXT, referrer TEXT, visits INTEGER DEFAULT 0)');
+	db.run('CREATE TABLE IF NOT EXISTS refs (shortUrl TEXT, referrer TEXT UNIQUE, visits INTEGER DEFAULT 0)');
 })
 
 app.use(express.json());