diff --git a/apps/member/views.py b/apps/member/views.py
index 6e088fe..be6de1c 100644
--- a/apps/member/views.py
+++ b/apps/member/views.py
@@ -1,5 +1,5 @@
 import random
-from datetime import datetime
+from datetime import timezone
 
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.contrib.auth.models import AnonymousUser
@@ -157,7 +157,7 @@ class DocumentView(LoginRequiredMixin, View):
 
         if isinstance(doc, Solution):
             for pool in doc.pools.all():
-                if pool.round == 2 and datetime.now() < doc.tournament.date_solutions_2:
+                if pool.round == 2 and timezone.now() < doc.tournament.date_solutions_2:
                     continue
                 if self.request.user.team in pool.teams.all():
                     grant = True
diff --git a/apps/tournament/models.py b/apps/tournament/models.py
index 2a32b80..6880cd5 100644
--- a/apps/tournament/models.py
+++ b/apps/tournament/models.py
@@ -46,27 +46,27 @@ class Tournament(models.Model):
     )
 
     date_inscription = models.DateTimeField(
-        default=datetime.now,
+        default=timezone.now,
         verbose_name=_("date of registration closing"),
     )
 
     date_solutions = models.DateTimeField(
-        default=datetime.now,
+        default=timezone.now,
         verbose_name=_("date of maximal solution submission"),
     )
 
     date_syntheses = models.DateTimeField(
-        default=datetime.now,
+        default=timezone.now,
         verbose_name=_("date of maximal syntheses submission for the first round"),
     )
 
     date_solutions_2 = models.DateTimeField(
-        default=datetime.now,
+        default=timezone.now,
         verbose_name=_("date when solutions of round 2 are available"),
     )
 
     date_syntheses_2 = models.DateTimeField(
-        default=datetime.now,
+        default=timezone.now,
         verbose_name=_("date of maximal syntheses submission for the second round"),
     )
 
diff --git a/apps/tournament/views.py b/apps/tournament/views.py
index 9a50449..cc6d6e2 100644
--- a/apps/tournament/views.py
+++ b/apps/tournament/views.py
@@ -1,6 +1,6 @@
 import random
 import zipfile
-from datetime import datetime
+from datetime import timezone
 from io import BytesIO
 
 from django.contrib.auth.mixins import LoginRequiredMixin
@@ -237,7 +237,7 @@ class SolutionsView(TeamMixin, BaseFormView, SingleTableView):
         solution.team = self.request.user.team
         solution.final = solution.team.selected_for_final
 
-        if datetime.now() > solution.tournament.date_solutions:
+        if timezone.now() > solution.tournament.date_solutions:
             form.add_error('file', _("You can't publish your solution anymore. Deadline: {date:%m-%d-%Y %h:%M}.")
                            .format(date=solution.tournament.date_solutions))
             return super().form_invalid(form)
@@ -341,13 +341,13 @@ class SynthesesView(TeamMixin, BaseFormView, SingleTableView):
         synthesis.team = self.request.user.team
         synthesis.final = synthesis.team.selected_for_final
 
-        if synthesis.round == '1' and datetime.now() > synthesis.tournament.date_syntheses:
+        if synthesis.round == '1' and timezone.now() > synthesis.tournament.date_syntheses:
             form.add_error('file', _("You can't publish your synthesis anymore for the first round."
                                      " Deadline: {date:%m-%d-%Y %h:%M}.")
                            .format(date=synthesis.tournament.date_syntheses))
             return super().form_invalid(form)
 
-        if synthesis.round == '2' and datetime.now() > synthesis.tournament.date_syntheses_2:
+        if synthesis.round == '2' and timezone.now() > synthesis.tournament.date_syntheses_2:
             form.add_error('file', _("You can't publish your synthesis anymore for the second round."
                                      " Deadline: {date:%m-%d-%Y %h:%M}.")
                            .format(date=synthesis.tournament.date_syntheses_2))