diff --git a/flaschengeist/plugins/schedule/event_controller.py b/flaschengeist/plugins/schedule/event_controller.py
index da72d98..dbc829d 100644
--- a/flaschengeist/plugins/schedule/event_controller.py
+++ b/flaschengeist/plugins/schedule/event_controller.py
@@ -169,9 +169,14 @@ def delete_job(job: Job):
 
 def assign_to_job(job: Job, user, value):
     service = Service.query.get((job.id, user._id))
-    if service:
-        service.value = value
+    if value < 0:
+        if not service:
+            raise BadRequest
+        db.session.delete(service)
     else:
-        service = Service(user_=user, value=value, job_=job)
-        db.session.add(service)
+        if service:
+            service.value = value
+        else:
+            service = Service(user_=user, value=value, job_=job)
+            db.session.add(service)
     db.session.commit()