diff --git a/dev/js/src/tutorial.js b/dev/js/src/tutorial.js
index 03a33a3..5573682 100644
--- a/dev/js/src/tutorial.js
+++ b/dev/js/src/tutorial.js
@@ -146,7 +146,7 @@
 	      t._iframe = d.createElement('iframe');
 	      t._iframe.setAttribute(
 	        'src',
-	        (t.getPage() || t.start) + '?embedded=true'
+          (t.getPage() || t.start + '?embedded=true')
 	      );
 
         const btn = buttonGroupClass.create(