diff --git a/addons/calendar/models/calendar.py b/addons/calendar/models/calendar.py
index ce9a0453dd5..dfb22c53c0e 100644
--- a/addons/calendar/models/calendar.py
+++ b/addons/calendar/models/calendar.py
@@ -1238,10 +1238,10 @@ class Meeting(models.Model):
         """ Compute rule string according to value type RECUR of iCalendar
             :return: string containing recurring rule (empty if no rule)
         """
-        if self.interval and self.interval < 0:
-            raise UserError(_('interval cannot be negative.'))
-        if self.count and self.count <= 0:
-            raise UserError(_('Event recurrence interval cannot be negative.'))
+        if self.interval <= 0:
+            raise UserError(_('The interval cannot be negative.'))
+        if self.end_type == 'count' and self.count <= 0:
+            raise UserError(_('The number of repetitions  cannot be negative.'))
 
         def get_week_string(freq):
             weekdays = ['mo', 'tu', 'we', 'th', 'fr', 'sa', 'su']