diff --git a/index.html b/index.html
index 82083e5..f8ef5b9 100644
--- a/index.html
+++ b/index.html
@@ -52,7 +52,7 @@
 			</p>
 		</header>
 		<main>
-			<form action="/api/toot" method="POST" onsubmit="onFormSubmit(this)">
+			<form id="js-s2f-form" action="/api/toot" method="POST">
 				<section>
 					<label for="text">Post text</label>
 					<textarea
diff --git a/lib/main.js b/lib/main.js
index db0727e..cb0ff8f 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -32,6 +32,7 @@ const INSTANCE_LIST_URL = "https://api.joinmastodon.org/servers";
 const LOCAL_STORAGE_KEY = "recentInstances";
 const RECENT_INSTANCES_SIZE = 5;
 
+const $form = document.querySelector("#js-s2f-form");
 const $instance = document.querySelector("#instance");
 const $instanceDatalist = document.querySelector("#instanceDatalist");
 
@@ -110,10 +111,8 @@ function rememberInstance(instance) {
 	);
 }
 
-// Used in HTML
-// eslint-disable-next-line no-unused-vars
-function onFormSubmit(form) {
-	const formData = new FormData(form);
+function onFormSubmit(event) {
+	const formData = new FormData(event.target);
 
 	if (formData.get("remember")) {
 		rememberInstance(formData.get("instance"));
@@ -140,3 +139,4 @@ if (prefillInstance != undefined) {
 }
 
 $instance.addEventListener("focus", loadInstances);
+$form.addEventListener("submit", onFormSubmit);