diff --git a/announce_url_title.py b/announce_url_title.py
index 019f8af..031243b 100644
--- a/announce_url_title.py
+++ b/announce_url_title.py
@@ -308,7 +308,7 @@ def purge_cb(*args):
     global urls
 
     t_now = now()
-    for url, url_d in urls.items():
+    for url, url_d in urls.copy():
         if (t_now - url_d['launched']) > \
             int(w.config_get_plugin('reannounce_wait'))*60:
                 del urls[url]