diff --git a/static/form.js b/static/form.js
index d5ab745..d1affc1 100644
--- a/static/form.js
+++ b/static/form.js
@@ -67,19 +67,19 @@ function knownTypes() {
   }
 
   // Get location in document.
-  let known_types = document.getElementById('knowntypes');
+  const known_types = document.getElementById('knowntypes');
   known_types.textContent = `Known types: `;
 
   // Create a button for every known type.
   for (let label of Object.keys(map).sort()) {
-      btn = document.createElement('button');
-      btn.setAttribute('type', 'button');
-      btn.textContent = label;
-      btn.addEventListener('click', function() {
-          document.getElementById('type').value = label;
-      });
+    btn = document.createElement('button');
+    btn.setAttribute('type', 'button');
+    btn.textContent = label;
+    btn.addEventListener('click', function() {
+      document.getElementById('type').value = label;
+    });
 
-      known_types.appendChild(btn);
+    known_types.appendChild(btn);
   }
 }