Index: applications/editors/josm/plugins/OpeningHoursEditor/src/org/openstreetmap/josm/plugins/ohe/gui/OheEditor.java
===================================================================
--- applications/editors/josm/plugins/OpeningHoursEditor/src/org/openstreetmap/josm/plugins/ohe/gui/OheEditor.java	(revision 24289)
+++ applications/editors/josm/plugins/OpeningHoursEditor/src/org/openstreetmap/josm/plugins/ohe/gui/OheEditor.java	(revision 24290)
@@ -306,4 +306,11 @@
                     / (getMinuteHeight() * TimeRect.minuteResterize))
                     * TimeRect.minuteResterize;
+            
+            // ensure that the new time is in a valid range
+            day1 = Math.max(day1, 0);
+            day1 = Math.min(day1, 6);
+            minute1 = Math.max(minute1, 0);
+            minute1 = Math.min(minute1, 24 * 60);
+            
             repaint();
         }