diff --git a/public/app.css b/public/app.css
index 49d02c2..e70fa04 100644
--- a/public/app.css
+++ b/public/app.css
@@ -170,4 +170,8 @@ body:not(.index) .page-title {
   margin: 0;
   background: none;
   color: var(--color-text);
-}
\ No newline at end of file
+}
+
+.error-message {
+  color: var(--color-danger);
+}
diff --git a/public/base.css b/public/base.css
index 7217e32..7bd5904 100644
--- a/public/base.css
+++ b/public/base.css
@@ -22,6 +22,7 @@
   --color-positive: var(--color-teal);
   --color-negative: var(--color-pink);
   --color-border: #DBDBDC;
+  --color-danger: #F00;
   --space-xs: 0.25em;
   --space-s: 0.5em;
   --space-m: 1em;
diff --git a/server.js b/server.js
index c12b838..e88ac7c 100644
--- a/server.js
+++ b/server.js
@@ -116,6 +116,11 @@ app.get("/signin", (request, response) => {
 })
 
 app.post("/signin", upload.none(), (request, response) => {
+  if (! request.body.name) {
+    response.status(422).render("signin", { title: "Sign In", error: true })
+    return;
+  }
+
   // Cookie expires in one day
   const expiration = new Date(Date.now() + 86400000)
 
diff --git a/views/signin.ejs b/views/signin.ejs
index d79d9fa..8004cb2 100644
--- a/views/signin.ejs
+++ b/views/signin.ejs
@@ -3,5 +3,8 @@
 <form method="post" enctype="multipart/form-data">
   <label for="name" class="display --block space --bottom-s">What is your name?</label>
   <input type="text" name="name" id="name" placeholder="Type your name…">
+  <% if (locals.error || false) { %>
+    <p class="error-message" data-turbo-cache="false">Name cannot be blank.</p>
+  <% } %>
   <button type="submit">Sign In</button>
 </form>