diff --git a/modules/default.nix b/modules/default.nix
index 60ee5637..ce462dd2 100644
--- a/modules/default.nix
+++ b/modules/default.nix
@@ -10,6 +10,7 @@
     ./image.nix
     ./persist
     ./ports.nix
+    ./root-on-tmpfs.nix
     ./services
     ./sops.nix
     ./ssh.nix
diff --git a/modules/persist/default.nix b/modules/persist/default.nix
index 16d6c0a4..4d4211c8 100644
--- a/modules/persist/default.nix
+++ b/modules/persist/default.nix
@@ -183,11 +183,6 @@ in
       default = false;
       type = types.bool;
     };
-    sane.persist.root-on-tmpfs = mkOption {
-      default = false;
-      type = types.bool;
-      description = "define / fs root to be a tmpfs. make sure to mount some other device to /nix";
-    };
     sane.persist.sys = mkOption {
       description = "directories (or files) to persist to disk, relative to the fs root /";
       default = {};
@@ -203,7 +198,6 @@ in
   };
 
   imports = [
-    ./root-on-tmpfs.nix
     ./stores
   ];
 
diff --git a/modules/persist/root-on-tmpfs.nix b/modules/persist/root-on-tmpfs.nix
deleted file mode 100644
index 5fd97622..00000000
--- a/modules/persist/root-on-tmpfs.nix
+++ /dev/null
@@ -1,16 +0,0 @@
-{ config, lib, ... }:
-
-let
-  cfg = config.sane.persist;
-in
-{
-  fileSystems."/" = lib.mkIf (cfg.enable && cfg.root-on-tmpfs) {
-    device = "none";
-    fsType = "tmpfs";
-    options = [
-      "mode=755"
-      "size=1G"
-      "defaults"
-    ];
-  };
-}
diff --git a/modules/root-on-tmpfs.nix b/modules/root-on-tmpfs.nix
new file mode 100644
index 00000000..3254ec25
--- /dev/null
+++ b/modules/root-on-tmpfs.nix
@@ -0,0 +1,22 @@
+{ config, lib, ... }:
+{
+  options = with lib; {
+    sane.root-on-tmpfs = mkOption {
+      default = false;
+      type = types.bool;
+      description = "define / fs root to be a tmpfs. make sure to mount some other device to /nix";
+    };
+  };
+
+  config = lib.mkIf config.sane.root-on-tmpfs {
+    fileSystems."/" = {
+      device = "none";
+      fsType = "tmpfs";
+      options = [
+        "mode=755"
+        "size=1G"
+        "defaults"
+      ];
+    };
+  };
+}