diff --git a/openslides/projector/models.py b/openslides/projector/models.py
index a9de923c8..7eca7acea 100644
--- a/openslides/projector/models.py
+++ b/openslides/projector/models.py
@@ -61,11 +61,16 @@ class SlideMixin(object):
 
     def delete(self, *args, **kwargs):
         """
-        Updates the projector, if the object is on the projector and is deleted.
+        Updates the projector if the object is on the projector and is deleted.
         """
         from openslides.projector.api import update_projector
+        # Checking active slide has to be done before calling super().delete()
+        # because super().delete() deletes the object and than we have no
+        # access to the former existing primary key any more. But updating
+        # projector has to be done after deleting the object of course.
+        update_required = self.is_active_slide()
         value = super(SlideMixin, self).delete(*args, **kwargs)
-        if self.is_active_slide():
+        if update_required:
             update_projector()
         return value
 
diff --git a/tests/projector/models.py b/tests/projector/models.py
new file mode 100644
index 000000000..6bfd3576d
--- /dev/null
+++ b/tests/projector/models.py
@@ -0,0 +1,11 @@
+from django.db import models
+
+from openslides.projector.models import SlideMixin
+
+
+class DummySlideMixinModel(SlideMixin, models.Model):
+    """
+    Dummy model to test the SlideMixin.
+    """
+    slide_callback_name = 'dummy_slides_mixin_model_geu3AiceeG9eo6ohChoD'
+    title = models.CharField(max_length=255)
diff --git a/tests/projector/test_models.py b/tests/projector/test_models.py
new file mode 100644
index 000000000..3a0618517
--- /dev/null
+++ b/tests/projector/test_models.py
@@ -0,0 +1,17 @@
+from mock import patch
+
+from openslides.config.api import config
+from openslides.utils.test import TestCase
+
+from .models import DummySlideMixinModel
+
+
+class TestSlideMixin(TestCase):
+    @patch('openslides.projector.api.update_projector')
+    def test_delete(self, mock_update_projector):
+        obj = DummySlideMixinModel.objects.create(title='title_cah4AhZai3einoh9koo3')
+        config['projector_active_slide'] = {
+            'callback': 'dummy_slides_mixin_model_geu3AiceeG9eo6ohChoD',
+            'pk': '1'}
+        obj.delete()
+        mock_update_projector.assert_called_with()
diff --git a/tests/settings.py b/tests/settings.py
index d913376e7..d7a181ead 100644
--- a/tests/settings.py
+++ b/tests/settings.py
@@ -29,6 +29,7 @@ DATABASES = {
 # Add OpenSlides plugins to this list
 INSTALLED_PLUGINS = (
     'tests.person_api',
+    'tests.projector',
     'tests.utils',
 )