diff --git a/src/panels/custom/ha-panel-custom.js b/src/panels/custom/ha-panel-custom.js
index 563f9d47f1..7571d697c5 100644
--- a/src/panels/custom/ha-panel-custom.js
+++ b/src/panels/custom/ha-panel-custom.js
@@ -98,7 +98,9 @@ It will have access to all data in Home Assistant.
`.trim();
const iframeDoc = this.querySelector("iframe").contentWindow.document;
iframeDoc.open();
- iframeDoc.write(``);
+ iframeDoc.write(
+ ``
+ );
iframeDoc.close();
}