diff --git a/modules/pubkeys.nix b/modules/pubkeys.nix
index 29e2e93..52dea77 100644
--- a/modules/pubkeys.nix
+++ b/modules/pubkeys.nix
@@ -3,11 +3,11 @@
 {
   options.fablab.pubkeys = with lib.types; {
     users = lib.mkOption {
-      type = attrsOf (listOf string);
+      type = attrsOf (listOf str);
       description = "pubkeys for a specific user";
     };
     groups = lib.mkOption {
-      type = attrsOf (listOf string);
+      type = attrsOf (listOf str);
       description = "pubkeys for a group of users";
     };
   };