diff --git a/combo_plugin_gnm/templatetags/gnm.py b/combo_plugin_gnm/templatetags/gnm.py
index beb3366..032700b 100644
--- a/combo_plugin_gnm/templatetags/gnm.py
+++ b/combo_plugin_gnm/templatetags/gnm.py
@@ -274,23 +274,25 @@ def get_slots_from_mairie_format(data, base_datetime):
         for days_list, time_table in parse_opening_hours_data(data):
             for weekday in days_list:
                 day_number = EN_ABBREV_WEEKDAYS_LIST.index(weekday)
-                start = openinghours_to_datetime(
-                    day_number, int(time_table['start_hour']), int(time_table['start_minute']), base_datetime)
-                end = openinghours_to_datetime(
-                    day_number, int(time_table['end_hour']), int(time_table['end_minute']), base_datetime)
+
+                start_hour = int(time_table['start_hour'])
+                start_minute = int(time_table['start_minute'])
+                end_hour = int(time_table['end_hour'])
+                end_minute = int(time_table['end_minute'])
+                start = openinghours_to_datetime(day_number, start_hour, start_minute, base_datetime)
 
                 # hours may belongs on next day
+                end_day_number = day_number
+                if end_hour < start_hour or end_hour == start_hour and end_minute < start_minute:
+                    end_day_number += 1
+                end = openinghours_to_datetime(end_day_number, end_hour, end_minute, base_datetime)
+
                 if end < start:
-                    tomorrow = day_number + 1
-                    end = openinghours_to_datetime(
-                        tomorrow, int(time_table['end_hour']), int(time_table['end_minute']), base_datetime)
-                    if end < start:
-                        # end time may be find this week whereas start time is picked on next week,
-                        # this occure if we are now past 24:00, on next day.
-                        # openinghours_to_datetime (return the next date and time after now())
-                        # can't return a coherent start time.
-                        # in this case we thrink the slot to the next day part.
-                        start = openinghours_to_datetime(tomorrow, 0, 0, base_datetime)
+                    # end time may be find this week whereas start time is picked on next week,
+                    # this occure if we are now past 24:00, on next day.
+                    # Compute start time from yesterday
+                    yesterday = base_datetime - datetime.timedelta(days=1)
+                    start = openinghours_to_datetime(day_number, start_hour, start_minute, yesterday)
 
                 timeslot = TimeSlot(start, end)
                 # add to slots the opening hours in chronological order beginning from today