diff --git a/ChangeLog b/ChangeLog
index 6891de90a..bb57307fc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-07-20  Mike Kestner  <mkestner@novell.com>
+
+	* gtk/Calendar.custom : workaround invalid states in widget when
+	raising month_changed signals.  [Fixes #78524]
+
 2007-07-20  Mike Kestner  <mkestner@novell.com>
 
 	* gtk/gtk-api-2.10.raw : refresh.
diff --git a/gtk/Calendar.custom b/gtk/Calendar.custom
index c20ae6ec9..a4ca0ab4a 100644
--- a/gtk/Calendar.custom
+++ b/gtk/Calendar.custom
@@ -26,7 +26,15 @@ public DateTime GetDate ()
 {
 	uint year, month, day;
 	GetDate (out year, out month, out day);
-	return new DateTime ((int) year, (int) month + 1, (int) day);
+	DateTime result;
+	try {
+		result = new DateTime ((int) year, (int) month + 1, (int) day);
+	} catch (ArgumentOutOfRangeException) {
+		// Kluge to workaround GtkCalendar being in an invalid state
+		// when raising month_changed signals, like in bug #78524.
+		result = new DateTime ((int) year, (int) month + 1, DateTime.DaysInMonth ((int) year, (int) month + 1));
+	}
+	return result;
 }