diff --git a/routes/5xx.html b/routes/5xx.html
deleted file mode 100644
index 7f008e0..0000000
--- a/routes/5xx.html
+++ /dev/null
@@ -1,22 +0,0 @@
-<svelte:head>
-	<title>Internal server error</title>
-</svelte:head>
-
-<h1>Internal server error</h1>
-
-<style>
-	h1 {
-		text-align: center;
-		margin: 0 auto;
-		font-size: 2.8em;
-		text-transform: uppercase;
-		font-weight: 700;
-		margin: 0 0 0.5em 0;
-	}
-
-	@media (min-width: 480px) {
-		h1 {
-			font-size: 4em;
-		}
-	}
-</style>
\ No newline at end of file
diff --git a/routes/4xx.html b/routes/_error.html
similarity index 66%
rename from routes/4xx.html
rename to routes/_error.html
index 9ff1ae7..72b3395 100644
--- a/routes/4xx.html
+++ b/routes/_error.html
@@ -1,20 +1,18 @@
 <svelte:head>
-	<title>Not found</title>
+	<title>{status}</title>
 </svelte:head>
 
-<h1>Not found</h1>
+<h1>{status}</h1>
 
-<p>Please check the URL</p>
+<p>{error.message}</p>
 
 <style>
 	h1, p {
-		text-align: center;
 		margin: 0 auto;
 	}
 
 	h1 {
 		font-size: 2.8em;
-		text-transform: uppercase;
 		font-weight: 700;
 		margin: 0 0 0.5em 0;
 	}
diff --git a/routes/blog/[slug].html b/routes/blog/[slug].html
index 61f4a97..27354be 100644
--- a/routes/blog/[slug].html
+++ b/routes/blog/[slug].html
@@ -46,14 +46,17 @@
 
 <script>
 	export default {
-		preload({ params, query }) {
-			// the `slug` parameter is available because this file
-			// is called [slug].html
-			const { slug } = params;
+		async preload({ params, query }) {
+			// the `slug` parameter is available because
+			// this file is called [slug].html
+			const res = await this.fetch(`blog/${params.slug}.json`);
+			const data = await res.json();
 
-			return this.fetch(`blog/${slug}.json`).then(r => r.json()).then(post => {
-				return { post };
-			});
+			if (res.status === 200) {
+				return { post: data };
+			} else {
+				this.error(res.status, data.message);
+			}
 		}
 	};
 </script>
\ No newline at end of file
diff --git a/routes/blog/[slug].json.js b/routes/blog/[slug].json.js
index cd8ab53..176890d 100644
--- a/routes/blog/[slug].json.js
+++ b/routes/blog/[slug].json.js
@@ -6,8 +6,8 @@ posts.forEach(post => {
 });
 
 export function get(req, res, next) {
-	// the `slug` parameter is available because this file
-	// is called [slug].json.js
+	// the `slug` parameter is available because
+	// this file is called [slug].json.js
 	const { slug } = req.params;
 
 	if (lookup.has(slug)) {
@@ -17,6 +17,12 @@ export function get(req, res, next) {
 
 		res.end(lookup.get(slug));
 	} else {
-		next();
+		res.writeHead(404, {
+			'Content-Type': 'application/json'
+		});
+
+		res.end(JSON.stringify({
+			message: `Not found`
+		}));
 	}
 }