diff --git a/ippisite/ippidb/forms.py b/ippisite/ippidb/forms.py
index db8999ac0bb2286d3c9644db3dfc13cc82a0fba8..44d7f4df7c1d8a50cbda956beb5bbc82804f6110 100644
--- a/ippisite/ippidb/forms.py
+++ b/ippisite/ippidb/forms.py
@@ -252,9 +252,9 @@ class ComplexCompositionForm(forms.Form):
     )
     domain = forms.ModelChoiceField(
         queryset=Domain.objects.none(),
-        required=True,
+        required=False,
         widget=forms.Select(attrs={'class': 'form-control'}),
-        empty_label=None,
+        empty_label="Unidentified",
     )
     ppc_copy_nb = forms.IntegerField(
         label="Number of copies of the protein in the complex",
@@ -289,7 +289,6 @@ class ComplexCompositionForm(forms.Form):
                 self.cleaned_data.get("ppp_copy_nb_per_p", None) is None:
             self.add_error("ppp_copy_nb_per_p", _("This field is required"))
 
-
 class ComplexCompositionBaseFormSet(forms.BaseFormSet):
     def full_clean(self):
         """