diff --git a/netbox/utilities/forms/fields/csv.py b/netbox/utilities/forms/fields/csv.py
index 0b33a1985..45428521c 100644
--- a/netbox/utilities/forms/fields/csv.py
+++ b/netbox/utilities/forms/fields/csv.py
@@ -114,6 +114,8 @@ class CSVMultipleContentTypeField(forms.ModelMultipleChoiceField):
 
     # TODO: Improve validation of selected ContentTypes
     def prepare_value(self, value):
+        if not value:
+            return None
         if type(value) is str:
             ct_filter = Q()
             for name in value.split(','):