diff --git a/app/common/BaseAPI.ts b/app/common/BaseAPI.ts
index b5294e84..17d9ff69 100644
--- a/app/common/BaseAPI.ts
+++ b/app/common/BaseAPI.ts
@@ -61,7 +61,7 @@ export class BaseAPI {
       'X-Requested-With': 'XMLHttpRequest',
       ...options.headers
     };
-    if ((window as any)?.isGristBootPage) {
+    if (typeof window !== 'undefined' && (window as any)?.isGristBootPage) {
       const parts = (new URL(window.location.href).pathname).split('/');
       if (parts[0] === '' && parts[1] === 'boot' && parts[2] !== undefined) {
         this._headers['X-Boot-Key'] = parts[2];