diff --git a/py/Boinc/boincxml.py b/py/Boinc/boincxml.py
index 29e56f8c25..ff12bbde3d 100644
--- a/py/Boinc/boincxml.py
+++ b/py/Boinc/boincxml.py
@@ -99,6 +99,9 @@ class ConfigDictList(list):
         new_cd      = ConfigDict(new_element)
         self.append(new_cd)
         return new_cd
+    def remove_node(self, item):
+        self.remove(item)
+        self._node.removeChild(item._node)
 
 class XMLConfig:
     '''Base class for xml config files'''
diff --git a/sched/start b/sched/start
index f1200bb325..3ca050c92f 100755
--- a/sched/start
+++ b/sched/start
@@ -438,14 +438,10 @@ def do_prune_run_states():
 
     if not prune_run_state:
         return
-    new_run_state_tasks = []
     for run_state_task in run_state.tasks:
         if run_state_task.prunable:
             print 'Deleting obsolete run_state task', run_state_task.cmd, '(last run %s)' %timestamp(float(run_state_task.last_run))
-        else:
-            new_run_state_tasks.append(run_state_task)
-    # replace all elements of existing ConfigDictList instead of assigning a new one
-    run_state.tasks[:] = new_run_state_tasks
+            run_state.tasks.remove_node(run_state_task)
 
 def stop_daemon(pid):
     '''returns 1 if something stopped, else 0'''