diff --git a/udata_front/frontend/helpers.py b/udata_front/frontend/helpers.py
index 922efaf3d..3a7858b83 100644
--- a/udata_front/frontend/helpers.py
+++ b/udata_front/frontend/helpers.py
@@ -287,19 +287,23 @@ def short_day(date):
 
 def daterange_with_details(value):
     '''Display a date range in the shorter possible maner.'''
-    delta = value.end - value.start
+    if value.end:
+        delta = value.end - value.start
+    else:
+        delta = None
+
     start, end = None, None
-    if is_first_year_day(value.start) and is_last_year_day(value.end):
+    if is_first_year_day(value.start) and (not value.end or is_last_year_day(value.end)):
         start = value.start.year
-        if delta.days > 365:
+        if delta and delta.days > 365:
             end = value.end.year
-    elif is_first_month_day(value.start) and is_last_month_day(value.end):
+    elif is_first_month_day(value.start) and (not value.end or is_last_month_day(value.end)):
         start = short_month(value.start)
-        if delta.days > 31:
+        if delta and delta.days > 31:
             end = short_month(value.end)
     else:
         start = short_day(value.start)
-        if value.start != value.end:
+        if value.end and value.start != value.end:
             end = short_day(value.end)
     return _('%(start)s to %(end)s', start=start, end=end) if end else start
 
@@ -314,13 +318,15 @@ def daterange(value, details=False):
     if details:
         return daterange_with_details(value)
 
-    date_format = '%Y'
 
-    delta = value.end - value.start
-    start, end = None, None
+    date_format = '%Y'
     start = value.start.strftime(date_format)
-    if delta.days > 365:
-        end = value.end.strftime(date_format)
+
+    end = None
+    if value.end:
+        delta = value.end - value.start
+        if delta.days > 365:
+            end = value.end.strftime(date_format)
 
     return '{start!s}–{end!s}'.format(start=start, end=end) if end else start