diff --git a/atlas/forms.py b/atlas/forms.py
index 47db9701..e91ffb3e 100755
--- a/atlas/forms.py
+++ b/atlas/forms.py
@@ -45,7 +45,7 @@ class SeriesFindingsForm(ModelForm):
             initial = kwargs.setdefault("initial", {})
             # The widget for a ModelMultipleChoiceField expects
             # a list of primary key for the selected data.
-            initial["series"] = kwargs["series_id"]
+            initial["series"] = kwargs.pop("series_id")
 
         super(SeriesFindingsForm, self).__init__(*args, **kwargs)