diff --git a/module.nix b/module.nix
index 70a742b..a30599a 100644
--- a/module.nix
+++ b/module.nix
@@ -3,7 +3,7 @@
 let
   cfg = config.services.gobot;
   defaultUser = "gobot";
-  inherit (lib) mkEnableOption mkMerge mkPackageOption mkOption mkIf types optionalAttrs;
+  inherit (lib) mkEnableOption mkMerge mkPackageOption mkOption mkIf types optionalAttrs optional optionalString;
 in
 {
   options.services.gobot = {
@@ -144,7 +144,7 @@ in
       script = ''
         export BOT_TOKEN="$(< $CREDENTIALS_DIRECTORY/BOT_TOKEN )"
         export MYSQL_PASSWORD="$(< $CREDENTIALS_DIRECTORY/MYSQL_PASSWORD )"
-        ${lib.optionalString (cfg.useWebhook && cfg.webhookSecretFile != null) ''
+        ${optionalString (cfg.useWebhook && cfg.webhookSecretFile != null) ''
         export WEBHOOK_SECRET="$(< $CREDENTIALS_DIRECTORY/WEBHOOK_SECRET )"
         ''}
 
@@ -155,8 +155,8 @@ in
         LoadCredential = [
           "BOT_TOKEN:${cfg.botTokenFile}"
           "MYSQL_PASSWORD:${cfg.database.passwordFile}"
-          (optionalAttrs (cfg.useWebhook && cfg.webhookSecretFile != null) "WEBHOOK_SECRET:${cfg.webhookSecretFile}")
-        ];
+        ] ++ optional (cfg.useWebhook && cfg.webhookSecretFile != null) "WEBHOOK_SECRET:${cfg.webhookSecretFile}";
+
         Restart = "always";
         User = cfg.user;
         Group = defaultUser;
@@ -177,7 +177,7 @@ in
           PORT = toString cfg.port;
           WEBHOOK_PUBLIC_URL = cfg.webhookPublicUrl;
           WEBHOOK_URL_PATH = cfg.webhookUrlPath;
-          WEBHOOK_SECRET = lib.optionalString (cfg.webhookSecret != null) cfg.webhookSecret;
+          WEBHOOK_SECRET = optionalString (cfg.webhookSecret != null) cfg.webhookSecret;
         })
       ];
     };