diff --git a/web/src/utils.ts b/web/src/utils.ts
index 8437925..f932446 100644
--- a/web/src/utils.ts
+++ b/web/src/utils.ts
@@ -28,7 +28,7 @@ export async function generateCode() {
       ciffers[Math.floor(Math.random() * 10)] +
       ciffers[Math.floor(Math.random() * 10)] +
       ciffers[Math.floor(Math.random() * 10)];
-    found = await prisma.opening.findFirst({ where: { code } });
+    found = await prisma.opening.findFirst({ where: { code, date: null } });
   } while (found);
   return code;
 }
diff --git a/web/src/webRouter.ts b/web/src/webRouter.ts
index 09b6113..82a8023 100644
--- a/web/src/webRouter.ts
+++ b/web/src/webRouter.ts
@@ -158,6 +158,17 @@ webRouter.get('/legal', async (request: Request, response: Response) => {
   return response.sendFile(path.join(__dirname, "../www/legal.html"));
 });
 
+webRouter.get('/cancel', async (request: Request, response: Response) => {
+  if (!chestAlive()) return response.redirect('/down');
+  const login = authenticate(request);
+  if (!login) return response.redirect('/login');
+  const opening = await getWaitingOpening(login);
+  if (opening && opening.type === 'borrow') {
+    await prisma.opening.update({ where: { id: opening.id }, data: { code: null, codeGeneratedAt: null } });
+  }
+  return response.redirect('/');
+});
+
 webRouter.get('/', async (request: Request, response: Response) => {
   if (!chestAlive()) return response.redirect('/down');
   const login = authenticate(request);