diff --git a/conntrackt/views.py b/conntrackt/views.py
--- a/conntrackt/views.py
+++ b/conntrackt/views.py
@@ -530,13 +530,13 @@ class EntityCreateView(RedirectToNextMix
         project_id = self.request.GET.get("project", None)
         if project_id:
             form.fields["project"].queryset = Project.objects.filter(pk=project_id)
-            form.fields["project"].widget.attrs["readonly"] = True
+            form.fields["project"].empty_label = None
 
         # Limit the location selection if required.
         location_id = self.request.GET.get("location", None)
         if location_id:
             form.fields["location"].queryset = Location.objects.filter(pk=location_id)
-            form.fields["location"].widget.attrs["readonly"] = True
+            form.fields["location"].empty_label = None
 
         return form
 
@@ -657,7 +657,7 @@ class InterfaceCreateView(RedirectToNext
         entity_id = self.request.GET.get("entity", None)
         if entity_id:
             form.fields["entity"].queryset = Entity.objects.filter(pk=entity_id)
-            form.fields["entity"].widget.attrs["readonly"] = True
+            form.fields["entity"].empty_label = False
 
         return form