diff --git a/demo-site/insertr/insertr.js b/demo-site/insertr/insertr.js
index 6da8a14..e6fdb16 100644
--- a/demo-site/insertr/insertr.js
+++ b/demo-site/insertr/insertr.js
@@ -302,7 +302,8 @@ class Insertr {
             // Check for headings
             if (line.match(/^#{1,6}\s/)) {
                 if (currentBlock) blocks.push(currentBlock);
-                const level = line.match(/^#+/)[0].length;
+                const hashMatch = line.match(/^#+/);
+                const level = hashMatch ? hashMatch[0].length : 1;
                 currentBlock = {
                     type: `h${level}`,
                     content: line.replace(/^#+\s*/, '').trim()