diff --git a/chrono/agendas/models.py b/chrono/agendas/models.py
index e340723a..c5c8ae17 100644
--- a/chrono/agendas/models.py
+++ b/chrono/agendas/models.py
@@ -16,7 +16,7 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 import datetime
-import fractions
+import math
 import requests
 import vobject
 
@@ -111,7 +111,7 @@ class Agenda(models.Model):
             raise ValueError()
         gcd = durations[0]
         for duration in durations[1:]:
-            gcd = fractions.gcd(duration, gcd)
+            gcd = math.gcd(duration, gcd)
         return gcd
 
     def export_json(self):