diff --git a/config.ru b/config.ru
index 8093387f..dbde9631 100644
--- a/config.ru
+++ b/config.ru
@@ -69,7 +69,7 @@ csp_options = {
   img_src: "'self' data:",
   report_uri: Sentry.csp_report_uri,
   report_ratio: 0.01,
-  frame_ancestors: 'none',
+  frame_ancestors: "'none'",
   form_action: "'self'"
 }.delete_if { |_, value| value.nil? || value=='' }