--- a/modules/nixos/secrets.nix
+++ b/modules/nixos/secrets.nix
@@ -11,7 +11,7 @@
   inherit (lib.lists) optional;
   inherit (lib.attrsets) mapAttrs;
   inherit (lib.modules) mkIf;
-  inherit (lib.types) submodule str attrsOf nullOr unspecified lazyAttrsOf;
+  inherit (lib.types) submodule str attrsOf nullOr unspecified lazyAttrsOf uniq functionTo package;
   inherit (fleetLib.strings) decodeRawSecret;
 
   sysConfig = config;
@@ -60,7 +60,7 @@
       };
 
       generator = mkOption {
-        type = nullOr unspecified;
+        type = uniq (nullOr (functionTo package));
         description = "Derivation to evaluate for secret generation";
         default = null;
       };
--- a/modules/secrets.nix
+++ b/modules/secrets.nix
@@ -4,7 +4,7 @@
   ...
 }: let
   inherit (lib.options) mkOption literalExpression;
-  inherit (lib.types) unspecified nullOr listOf str bool attrsOf submodule functionTo package unique;
+  inherit (lib.types) unspecified nullOr listOf str bool attrsOf submodule functionTo package uniq;
   inherit (lib.strings) concatStringsSep;
   inherit (lib.attrsets) mapAttrs;
 
@@ -41,7 +41,7 @@
         '';
       };
       generator = mkOption {
-        type = nullOr (unique (functionTo package));
+        type = uniq (nullOr (functionTo package));
         description = ''
           Function evaluating to nix derivation responsible for (re)generating the secret's content.