diff --git a/nixos/modules/services/misc/portunus.nix b/nixos/modules/services/misc/portunus.nix
index 58dd3591172c..7036a372d1ea 100644
--- a/nixos/modules/services/misc/portunus.nix
+++ b/nixos/modules/services/misc/portunus.nix
@@ -249,6 +249,7 @@ in
             acmeDirectory = config.security.acme.certs."${cfg.domain}".directory;
           in
           {
+            PORTUNUS_SERVER_HTTP_SECURE = "true";
             PORTUNUS_SLAPD_TLS_CA_CERTIFICATE = "/etc/ssl/certs/ca-certificates.crt";
             PORTUNUS_SLAPD_TLS_CERTIFICATE = "${acmeDirectory}/cert.pem";
             PORTUNUS_SLAPD_TLS_DOMAIN_NAME = cfg.domain;