diff --git a/bocal/settings_base.py b/bocal/settings_base.py
index a5f217c..22ff30a 100644
--- a/bocal/settings_base.py
+++ b/bocal/settings_base.py
@@ -87,7 +87,7 @@ AUTH_PASSWORD_VALIDATORS = [
 
 AUTHENTICATION_BACKENDS = [
     'django.contrib.auth.backends.ModelBackend',
-    'django_cas_ng.backends.CASBackend',
+    'mainsite.cas_backend.BOcalCASBackend',
 ]
 
 CAS_ADMIN_PREFIX = '/yaes5eiS'  # we don't want CAS to take over /admin auth
diff --git a/mainsite/cas_backend.py b/mainsite/cas_backend.py
new file mode 100644
index 0000000..a9abe05
--- /dev/null
+++ b/mainsite/cas_backend.py
@@ -0,0 +1,7 @@
+from django_cas_ng.backends import CASBackend
+
+
+class BOcalCASBackend(CASBackend):
+    # Partly from Robin Champenois's "ExperiENS". Thanks!
+    def clean_username(self, username):
+        return username.lower().strip()