diff --git a/bijoe/views.py b/bijoe/views.py
index df347cc..f2b3115 100644
--- a/bijoe/views.py
+++ b/bijoe/views.py
@@ -41,7 +41,7 @@ from .visualization.utils import Visualization as VisuUtil
 
 class AuthorizationMixin(object):
     def authorize(self, request):
-        if request.user.is_authenticated():
+        if request.user.is_authenticated:
             if not request.user.is_superuser:
                 raise PermissionDenied(_('You must be superuser'))
             return True
diff --git a/bijoe/visualization/views.py b/bijoe/visualization/views.py
index 6b90228..6500458 100644
--- a/bijoe/visualization/views.py
+++ b/bijoe/visualization/views.py
@@ -184,7 +184,7 @@ class VisualizationView(views.AuthorizationMixin, CubeDisplayMixin, DetailView):
 
 class SignatureAuthorizationMixin(views.AuthorizationMixin):
     def authorize(self, request):
-        if request.user.is_authenticated() and request.user.is_superuser:
+        if request.user.is_authenticated and request.user.is_superuser:
             return True
         if 'signature' in request.GET:
             signature = request.path + settings.SECRET_KEY
@@ -230,7 +230,7 @@ class VisualizationsJSONView(MultipleObjectMixin, View):
     model = models.Visualization
 
     def get(self, request, *args, **kwargs):
-        if not request.user.is_authenticated() or not request.user.is_superuser:
+        if not request.user.is_authenticated or not request.user.is_superuser:
             known_services = getattr(settings, 'KNOWN_SERVICES', [])
             if known_services:
                 key = None