diff --git a/zfs.nix b/zfs.nix
index a94f8d9..14a9270 100644
--- a/zfs.nix
+++ b/zfs.nix
@@ -20,10 +20,13 @@ in
   boot.zfs.package = pkgs.zfs_unstable;
   boot.initrd.kernelModules = [ "zfs" ];
 
-  boot.kernelParams = [
-    # 2048MB
-    "zfs.zfs_arc_max=2048000000"
-  ];
+  boot.kernelParams =
+    let
+      mb = 4096;
+    in
+    [
+      "zfs.zfs_arc_max=${mb * 1000000}"
+    ];
 
   boot.supportedFilesystems = [ "zfs" ];
   boot.zfs.extraPools = [