diff --git a/lib/pleroma/plugs/http_security_plug.ex b/lib/pleroma/plugs/http_security_plug.ex
index 13423ca3f..472a3ff42 100644
--- a/lib/pleroma/plugs/http_security_plug.ex
+++ b/lib/pleroma/plugs/http_security_plug.ex
@@ -145,7 +145,7 @@ defp build_csp_param(url) when is_binary(url) do
     %{host: host, scheme: scheme} = URI.parse(url)
 
     if scheme do
-      scheme <> "://" <> host
+      [scheme, "://", host]
     end
   end