diff --git a/src/c3nav/mapdata/cache.py b/src/c3nav/mapdata/cache.py
index 55966dd7..f8a1619e 100644
--- a/src/c3nav/mapdata/cache.py
+++ b/src/c3nav/mapdata/cache.py
@@ -177,9 +177,10 @@ class MapHistory:
     def simplify(self):
         logging.info('simplify!')
         # remove updates that have no longer any array cells
-        new_updates = ((update, (self.data == i)) for i, update in enumerate(self.updates))
+        new_updates = ((i, update, (self.data == i)) for i, update in enumerate(self.updates))
         logging.info('before: %s' % (self.updates, ))
-        self.updates, new_affected = zip(*((update, affected) for update, affected in new_updates if affected.any()))
+        self.updates, new_affected = zip(*((update, affected) for i, update, affected in new_updates
+                                           if i == 0 or affected.any()))
         logging.info('after: %s' % (self.updates, ))
         for i, affected in enumerate(new_affected):
             self.data[affected] = i