diff --git a/src/baseClient.ts b/src/baseClient.ts
index 3ed34eb..50a6c30 100644
--- a/src/baseClient.ts
+++ b/src/baseClient.ts
@@ -69,6 +69,7 @@ export class ClasschartsClient {
         Authorization: "Basic " + this.sessionId,
         ...kyOptions.headers,
       },
+      credentials: undefined,
     } satisfies KyOptions;
     if (options?.revalidateToken === true && this.lastPing) {
       if (Date.now() - this.lastPing + 5000 > PING_INTERVAL) {
diff --git a/src/parentClient.ts b/src/parentClient.ts
index 08bac3a..dafad5c 100644
--- a/src/parentClient.ts
+++ b/src/parentClient.ts
@@ -41,6 +41,7 @@ export class ParentClient extends ClasschartsClient {
       method: "POST",
       body: formData,
       headers: headers,
+      credentials: undefined,
     });
     if (response.status != 302 || !response.headers.get("set-cookie"))
       throw new Error(
diff --git a/src/studentClient.ts b/src/studentClient.ts
index 1847434..1fceae1 100644
--- a/src/studentClient.ts
+++ b/src/studentClient.ts
@@ -37,6 +37,7 @@ export class StudentClient extends ClasschartsClient {
       body: formData,
       redirect: "manual",
       throwHttpErrors: false,
+      credentials: undefined,
     });
     if (request.status != 302 || !request.headers.get("set-cookie")) {
       throw new Error(