diff --git a/django/contrib/admin/views/stages/add.py b/django/contrib/admin/views/stages/add.py
index d4c475d874..fc23616064 100644
--- a/django/contrib/admin/views/stages/add.py
+++ b/django/contrib/admin/views/stages/add.py
@@ -51,8 +51,9 @@ def add_stage(request, path, show_delete=False, form_url='', post_url='../change
         # Add default data.
         new_data = manipulator.flatten_data()
 
-        # Override the defaults with request.GET, if it exists.
-        new_data.update(request.GET)
+        # Override the defaults with GET params, if they exist.
+        new_data.update(dict(request.GET.items()))
+
         errors = {}
 
     # Populate the FormWrapper.