diff --git a/ChangeLog b/ChangeLog
index 2c0094e50..338b3fad3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2008-12-30  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
+
+	* UI/Scheduler/UIxCalListingActions.m ([UIxCalListingActions
+	-eventsBlocksAction]): fixed a crash occuring in the rare
+	situation where an event end date would be inferior than its start
+	date.
+
 2008-12-23  Ludovic Marcotte  <lmarcotte@inverse.ca>
 
 	* SoObjects/Appointments/SOGoAppointmentFolder.{h,m}
diff --git a/UI/Scheduler/UIxCalListingActions.m b/UI/Scheduler/UIxCalListingActions.m
index a0751c4f5..3ef5c0eea 100644
--- a/UI/Scheduler/UIxCalListingActions.m
+++ b/UI/Scheduler/UIxCalListingActions.m
@@ -371,8 +371,14 @@ static inline void
 _feedBlockWithDayBasedData(NSMutableDictionary *block, unsigned int start,
 			   unsigned int end, unsigned int dayStart)
 {
-  unsigned int delta, quarterStart, length;
-
+  unsigned int delta, quarterStart, length, swap;
+  
+  if (start > end)
+    {
+      swap = end;
+      end = start;
+      start = swap;
+    }
   quarterStart = (start - dayStart) / quarterLength;
   delta = end - dayStart;
   if ((delta % quarterLength))