diff --git a/src/node/stack.rs b/src/node/stack.rs
index f6bf662..d6bea7c 100644
--- a/src/node/stack.rs
+++ b/src/node/stack.rs
@@ -190,10 +190,10 @@ pub async fn check_compose(arion_bin: &Path, source: &str) -> Result<()> {
     // Check that it's a valid nix tree
     rnix::Root::parse(source)
         .ok()
-        .map_err(|_| AppError::Client {
+        .map_err(|err| AppError::Client {
             status: StatusCode::NOT_ACCEPTABLE,
             code: "failed-nix-parse",
-            message: "The provided source is not valid Nix".to_string(),
+            message: format!("Parse error: {}", err),
         })?;
 
     // Create a temporary stack and check that it generates a YAML tree
@@ -215,7 +215,7 @@ pub async fn check_compose(arion_bin: &Path, source: &str) -> Result<()> {
         Err(AppError::Client {
             status: StatusCode::NOT_ACCEPTABLE,
             code: "failed-arion-check",
-            message: err,
+            message: format!("Arion {}", err),
         })
     } else {
         Ok(())
diff --git a/src/route/stack.rs b/src/route/stack.rs
index fc36157..29315de 100644
--- a/src/route/stack.rs
+++ b/src/route/stack.rs
@@ -74,6 +74,9 @@ async fn create_stack(
     State(state): State<AppState>,
     Form(form): Form<CreateStackForm>,
 ) -> Result<Redirect, AppError> {
+    // Make sure body is is ok
+    check_compose(&state.arion_bin, &form.source).await?;
+
     create_new(state.repository, &form.name, &form.source).await?;
 
     Ok(Redirect::to(format!("/stack/{}/", form.name).as_str()))
@@ -107,6 +110,9 @@ async fn edit_stack(
     // Cleanup source (like line endings)
     let source = form.source.replace("\r\n", "\n");
 
+    // Make sure file is ok
+    check_compose(&state.arion_bin, &source).await?;
+
     // Write compose file
     write_compose(&state.stack_dir, &stack_name, &source).await?;
 
diff --git a/static/css/editor.css b/static/css/editor.css
index c5835c6..6eafaff 100644
--- a/static/css/editor.css
+++ b/static/css/editor.css
@@ -17,6 +17,15 @@
 			}
 		}
 	}
+
+
+	& .error {
+		border-radius: 3px;
+		background-color: #500F1C;
+		color: #FF9592;
+		padding: 4px 8px;
+		display: none;
+	}
 }
 
 #editor {
@@ -28,4 +37,12 @@
 	min-height: 50vh;
 	border: 3px solid #5958B1;
 	border-radius: 3px;
+
+	&.checked {
+		border-color: #46A758;
+	}
+
+	&.err {
+		border-color: #E5484D;
+	}
 }
\ No newline at end of file
diff --git a/static/css/screen.css b/static/css/screen.css
index 0e10bb4..db1b494 100644
--- a/static/css/screen.css
+++ b/static/css/screen.css
@@ -121,4 +121,9 @@ textarea {
 	background-color: var(--bg-raised);
 	color: var(--text);
 	padding: 4px;
+}
+
+pre {
+	margin: 0;
+	padding: 0;
 }
\ No newline at end of file
diff --git a/static/js/compose.mjs b/static/js/compose.mjs
new file mode 100644
index 0000000..81fb0c5
--- /dev/null
+++ b/static/js/compose.mjs
@@ -0,0 +1,47 @@
+/**
+ * Checks if a specificied source is a valid arion-compose.nix file
+ * @param {string} source Source to check
+ * @returns {Promise<CheckResult>} Result of the check
+ */
+export async function check_compose(source) {
+	const response = await fetch("/stack/_/check", {
+		method: "POST",
+		headers: {
+			"Accept": "application/json",
+			"Content-Type": "text/plain",
+		},
+		body: source
+	});
+
+	if (response.ok) {
+		return { ok: true };
+	} else {
+		return { ok: false, error: await response.json() };
+	}
+}
+
+/**
+ * @typedef {Object} APIError
+ * @property {string} code - Error code
+ */
+
+/**
+ * @typedef {Object} CheckSuccess
+ * @property { true } ok - Indicates that the check was successful
+ * /
+
+/**
+ * @typedef {Object} APIError
+ * @property {string} code - Unique error code
+ * @property {string} message - Human readable error details
+ */
+
+/**
+ * @typedef {Object} CheckFailure
+ * @property {false} ok - Indicates that the check has failed
+ * @property {APIError} error - Info about the encountered error
+ */
+
+/**
+ * @typedef {CheckSuccess | CheckFailure} CheckResult
+ */
\ No newline at end of file
diff --git a/static/js/enhancements/check.mjs b/static/js/enhancements/check.mjs
new file mode 100644
index 0000000..505c581
--- /dev/null
+++ b/static/js/enhancements/check.mjs
@@ -0,0 +1,45 @@
+import Editor from "../ace.mjs";
+import { check_compose } from "/static/js/compose.mjs";
+
+/**
+ * Makes the form require the stack to be checked before submitting
+ * @param {HTMLFormElement} form 
+ * @param {Editor} editor 
+ */
+export function add_check(form, editor) {
+	form.addEventListener("submit", (ev) => {
+		ev.preventDefault();
+		check_stack(editor).then((result) => {
+			if (result) {
+				form.submit();
+			}
+		})
+		return false;
+	});
+}
+
+/**
+ * Runs the check function and updates some DOM elements
+ * @param {Editor} editor Editor instance
+ * @returns true if the stack is valid, false otherwise
+ */
+export async function check_stack(editor) {
+	const source = editor.editor.getValue();
+	const check_result = await check_compose(source);
+
+	const editorEl = document.querySelector(".ace_editor");
+	const editorErrorEl = document.querySelector("#editor-form .error");
+	editorEl.classList.remove("err", "checked");
+	editorErrorEl.style.display = "block";
+	editorErrorEl.classList.add("pending");
+	editorErrorEl.innerHTML = "Checking...";
+	if (check_result.ok) {
+		editorEl.classList.add("checked");
+		editorErrorEl.style.display = "";
+	} else {
+		editorEl.classList.add("err");
+		editorErrorEl.classList.remove("pending");
+		editorErrorEl.innerHTML = check_result.error.message;
+	}
+	return check_result.ok;
+}
\ No newline at end of file
diff --git a/templates/stack/get-one.html b/templates/stack/get-one.html
index a66fc36..7a37702 100644
--- a/templates/stack/get-one.html
+++ b/templates/stack/get-one.html
@@ -37,6 +37,7 @@
 	<section class="editor">
 		<h2>Editor</h2>
 		<form method="POST" action="./edit" id="editor-form">
+			<div class="error"></div>
 			<textarea name="source" id="editor">{{file_contents}}</textarea>
 			<div class="row">
 				<input style="flex:1" name="commit_message" type="text"
@@ -60,11 +61,6 @@
 		text-transform: uppercase;
 	}
 
-	pre {
-		margin: 0;
-		padding: 0;
-	}
-
 	.containers {
 		& .status {
 			text-align: center;
@@ -101,31 +97,15 @@
 	}
 </style>
 
-
 <script type="module">
 	import Editor from "/static/js/ace.mjs";
+	import { add_check } from "/static/js/enhancements/check.mjs";
 
 	const editor = new Editor("editor");
 
-	/* Add extra buttons */
-	const extraContainer = document.getElementById("editor-extra");
-
-	/* Check button */
-	const checkButton = document.createElement("button");
-	checkButton.appendChild(document.createTextNode("Check"));
-	checkButton.type = "button";
-	checkButton.addEventListener("click", async () => {
-		const body = editor.editor.getValue();
-		const response = await fetch("/stack/_/check", {
-			method: "POST",
-			headers: {
-				"Accept": "application/json",
-				"Content-Type": "text/plain",
-			},
-			body
-		});
-	})
-	extraContainer.appendChild(checkButton);
+	/* Enforce check pre-submit */
+	const form = document.getElementById("editor-form");
+	add_check(form, editor);
 </script>
 
 {% endblock %}
\ No newline at end of file
diff --git a/templates/stack/new-form.html b/templates/stack/new-form.html
index a282d1a..13e46cc 100644
--- a/templates/stack/new-form.html
+++ b/templates/stack/new-form.html
@@ -12,6 +12,7 @@
 			<div class="row">
 				<input style="flex:1" name="name" type="text" placeholder="Stack name" required />
 			</div>
+			<div class="error"></div>
 			<textarea name="source" id="editor" required>{}</textarea>
 			<div class="row">
 				<button type="submit">Create & Deploy</button>
@@ -31,8 +32,13 @@
 
 <script type="module">
 	import Editor from "/static/js/ace.mjs";
+	import { add_check } from "/static/js/enhancements/check.mjs";
 
 	const editor = new Editor("editor");
+
+	/* Enforce check pre-submit */
+	const form = document.getElementById("editor-form");
+	add_check(form, editor);
 </script>
 
 {% endblock %}
\ No newline at end of file