diff --git a/netbox/dcim/api/serializers.py b/netbox/dcim/api/serializers.py
index 8cfc9502e..c2cb846a9 100644
--- a/netbox/dcim/api/serializers.py
+++ b/netbox/dcim/api/serializers.py
@@ -886,7 +886,7 @@ class FrontPortSerializer(NetBoxModelSerializer, LinkTerminationSerializer):
 class ModuleBaySerializer(NetBoxModelSerializer):
     url = serializers.HyperlinkedIdentityField(view_name='dcim-api:modulebay-detail')
     device = NestedDeviceSerializer()
-    installed_module = ModuleBayNestedModuleSerializer()
+    installed_module = ModuleBayNestedModuleSerializer(required=False, allow_null=True)
 
     class Meta:
         model = ModuleBay
diff --git a/netbox/dcim/tests/test_filtersets.py b/netbox/dcim/tests/test_filtersets.py
index 63456b948..47aa9368c 100644
--- a/netbox/dcim/tests/test_filtersets.py
+++ b/netbox/dcim/tests/test_filtersets.py
@@ -1852,7 +1852,7 @@ class ModuleTestCase(TestCase, ChangeLoggedFilterSetTests):
     def test_module_bay(self):
         module_bays = ModuleBay.objects.all()[:2]
         params = {'module_bay_id': [module_bays[0].pk, module_bays[1].pk]}
-        self.assertEqual(self.filterset(params, self.queryset).qs.count(), 1)
+        self.assertEqual(self.filterset(params, self.queryset).qs.count(), 2)
 
     def test_device(self):
         device_types = Device.objects.all()[:2]