diff --git a/nixos/modules/virtualisation/virtualbox-image.nix b/nixos/modules/virtualisation/virtualbox-image.nix
index 071edda8269..cd356b9d382 100644
--- a/nixos/modules/virtualisation/virtualbox-image.nix
+++ b/nixos/modules/virtualisation/virtualbox-image.nix
@@ -18,6 +18,13 @@ in {
           The size of the VirtualBox base image in MiB.
         '';
       };
+      baseImageFreeSpace = mkOption {
+        type = with types; int;
+        default = 30 * 1024;
+        description = ''
+          Free space in the VirtualBox base image in MiB.
+        '';
+      };
       memorySize = mkOption {
         type = types.int;
         default = 1536;
@@ -117,6 +124,7 @@ in {
       inherit pkgs lib config;
       partitionTableType = "legacy";
       diskSize = cfg.baseImageSize;
+      additionalSpace = "${toString cfg.baseImageFreeSpace}M";
 
       postVM =
         ''