diff --git a/static/_headers b/static/_headers
index 46528c7..c04437d 100644
--- a/static/_headers
+++ b/static/_headers
@@ -1,7 +1,7 @@
 /*
   Link: <https://erambler.superfeedr.com/>; rel="hub"
   Permissions-Policy: interest-cohort=()
-  Content-Security-Policy: frame-ancestors 'self'
+  Content-Security-Policy: frame-ancestors 'self'; default-src https:
   X-Frame-Options: SAMEORIGIN
   X-Content-Type-Options: nosniff
   X-XSS-Protection: 1; mode=block