diff --git a/templates/conf.php.j2 b/templates/conf.php.j2
index 9d186e4..8a8458b 100644
--- a/templates/conf.php.j2
+++ b/templates/conf.php.j2
@@ -101,7 +101,7 @@ icon = {{ private_bin_main_icon }}
 ;   webassembly support (used for zlib compression). You can remove it if Chrome
 ;   doesn't need to be supported and old browsers don't need to be warned.
 {% if private_bin_main_url_shortener is not none %}
-cspheader = {{ private_bin_main_cspheader }}
+cspheader = "{{ private_bin_main_cspheader }}"
 {% else %}
 ; cspheader = "default-src 'none'; manifest-src 'self'; connect-src * blob:; script-src 'self' 'unsafe-eval'; style-src 'self'; font-src 'self'; img-src 'self' data: blob:; media-src blob:; object-src blob:; sandbox allow-same-origin allow-scripts allow-forms allow-popups allow-modals"
 {% endif %}