diff --git a/earwigbot/wiki/copyvios/workers.py b/earwigbot/wiki/copyvios/workers.py
index 691fa6f..c66e197 100644
--- a/earwigbot/wiki/copyvios/workers.py
+++ b/earwigbot/wiki/copyvios/workers.py
@@ -128,7 +128,7 @@ class _CopyvioWorker(object):
         url = source.url.encode("utf8")
         try:
             response = self._opener.open(url, timeout=source.timeout)
-        except (URLError, HTTPException, socket_error):
+        except (URLError, HTTPException, socket_error, ValueError):
             return None
 
         try: