diff --git a/app/terraform/block_mirror.py b/app/terraform/block_mirror.py
index a62caaa..a93a72e 100644
--- a/app/terraform/block_mirror.py
+++ b/app/terraform/block_mirror.py
@@ -26,7 +26,7 @@ class BlockMirrorAutomation(BaseAutomation):
         self.parse()
         logging.debug("Parse complete")
         rotated = []
-        proxy_urls = active_proxy_urls()
+        proxy_urls = list(filter(lambda u: u is not None, active_proxy_urls()))
         for pattern in self.patterns:
             blocked_urls = fnmatch.filter(proxy_urls, pattern)
             for blocked_url in blocked_urls: