diff --git a/hosts/nixos-testbed/configuration.nix b/hosts/nixos-testbed/configuration.nix
index 7bbb8d9..adacc83 100644
--- a/hosts/nixos-testbed/configuration.nix
+++ b/hosts/nixos-testbed/configuration.nix
@@ -51,6 +51,13 @@
     };
   };
 
+  # HACK: This is here temporarily so I can use `/persist` without
+  # Impermanence.  This can be removed once impermanence is enabled.
+  # Create a group called `cfg.persistGroupName`
+  users.groups.persist = {
+    name = "persist";
+  };
+
   # HACK: This is here temporarily so I can use `/persist` without
   # Impermanence.  This can be removed once impermanence is enabled.
   systemd.tmpfiles.settings = {
diff --git a/users/crumb/default.nix b/users/crumb/default.nix
index ea5632d..310a660 100644
--- a/users/crumb/default.nix
+++ b/users/crumb/default.nix
@@ -1,6 +1,8 @@
 {
-  systemConfiguration = {
+  systemConfiguration = { config, ... }: {
     isNormalUser = true;
+    # TODO: Don't hard-code `persist`.  Use
+    # config.sydnix.impermanence.persistGroupName.
     extraGroups = [ "wheel" "persist" ];
     # Change this immediately after installation!
     initialPassword = "password123";