diff --git a/src/views/gcal-week-header.c b/src/views/gcal-week-header.c
index 8168e7e3..ae92a32c 100644
--- a/src/views/gcal-week-header.c
+++ b/src/views/gcal-week-header.c
@@ -367,9 +367,10 @@ update_overflow (GcalWeekHeader *self)
           gtk_label_set_label (GTK_LABEL (label), text);
           g_free (text);
         }
-      else
+      else if (label)
         {
-          g_clear_pointer (&self->overflow_label[i], gtk_widget_destroy);
+          gtk_widget_destroy (label);
+          self->overflow_label[i] = NULL;
         }
     }
 
@@ -1668,6 +1669,13 @@ gcal_week_header_add_event (GcalWeekHeader *self,
   else
     end = 6;
 
+  /* Sanity checks */
+  if (start > end || start > 6 || end < 0)
+    {
+      g_warning ("Error adding event '%s' to the week header", gcal_event_get_summary (event));
+      return;
+    }
+
   /* Add the event widget to the grid */
   add_event_to_grid (self, event, start, end);