diff --git a/src/util.ts b/src/util.ts
index 649ee02..7976248 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -1,20 +1,18 @@
 export function instanceKeepAlive(instanceId: string, token: string) {
-    fetch(`https://api.rerobots.net/instance/${instanceId}/ka`, {
+    return fetch(`https://api.rerobots.net/instance/${instanceId}/ka`, {
         method: 'POST',
         headers: {
             Authorization: 'Bearer ' + token,
             'Content-Type': 'application/json',
         },
-    })
-        .then((res) => {
-            if (res.ok) {
-                setTimeout(() => {
-                    instanceKeepAlive(instanceId, token);
-                }, 45000);
-                return;
-            }
-        })
-        .catch((err) => {
-            console.log(err);
-        });
+    }).then((res) => {
+        if (res.ok) {
+            setTimeout(() => {
+                instanceKeepAlive(instanceId, token);
+            }, 45000);
+            return;
+        } else if (res.status < 404) {
+            throw new Error(`${res.status}`);
+        }
+    });
 }
diff --git a/tests/instanceKeepAlive.test.ts b/tests/instanceKeepAlive.test.ts
new file mode 100644
index 0000000..d6aea08
--- /dev/null
+++ b/tests/instanceKeepAlive.test.ts
@@ -0,0 +1,7 @@
+import { instanceKeepAlive } from '../src/util';
+
+test('unauthenticated calls fail', () => {
+    return expect(
+        instanceKeepAlive('1926b858-0d00-4b84-b7ca-5c56be880525', ''),
+    ).rejects.toThrow();
+});