diff --git a/src/Snippets.js b/src/Snippets.js
index b798e3db..a58c6593 100644
--- a/src/Snippets.js
+++ b/src/Snippets.js
@@ -5,7 +5,7 @@ import warn from './utils/warn'
 const Snippets = {
   tags: function ({ id, events, dataLayer, dataLayerName, preview, auth }) {
     const gtm_auth = `&gtm_auth=${auth}`
-    const gtm_preview = `&gtm_preview=${preview}`
+    const gtm_preview = !preview ? '' : `&gtm_preview=${preview}`
 
     if (!id) warn('GTM Id is required')