diff --git a/vm.nix b/vm.nix
index cf86026..039c82b 100644
--- a/vm.nix
+++ b/vm.nix
@@ -27,7 +27,8 @@ let
       ${pkgs.qemu}/bin/qemu-img create -f qcow2 \
         -b "${debianImage}" \
         -F qcow2 \
-        "${vmDataDir}/debian-persistent.qcow2"
+        "${vmDataDir}/debian-persistent.qcow2" \
+        20G
     fi
     
     # Create cloud-init configuration