diff --git a/doc/sandbox.mdwn b/doc/sandbox.mdwn
index 9c13513df..a536303d2 100644
--- a/doc/sandbox.mdwn
+++ b/doc/sandbox.mdwn
@@ -19,6 +19,7 @@ Here's another one with *emphasised* text.
 > > This is nested blockquote.
 >
 >> And without a space works too.
+>>> to three levels
 >
 > Back to the first level.