diff --git a/quiz_atomes/forms.py b/quiz_atomes/forms.py
index c945156..4e72c8b 100644
--- a/quiz_atomes/forms.py
+++ b/quiz_atomes/forms.py
@@ -5,7 +5,7 @@ from django.utils.translation import gettext_lazy as _
 from .models import User
 
 def validate_login(value):
-    if len(User.objects.filter(login=value)) == 0:
+    if len(User.objects.filter(login=value.lower())) == 0:
         raise ValidationError(
             _("Ce login n'existe pas"),
             params={'value': value},