diff --git a/nixos/modules/virtualisation/oci-image.nix b/nixos/modules/virtualisation/oci-image.nix
index d4af5016dd71..1e2b90bfd46e 100644
--- a/nixos/modules/virtualisation/oci-image.nix
+++ b/nixos/modules/virtualisation/oci-image.nix
@@ -9,10 +9,10 @@ in
   config = {
     system.build.OCIImage = import ../../lib/make-disk-image.nix {
       inherit config lib pkgs;
+      inherit (cfg) diskSize;
       name = "oci-image";
       configFile = ./oci-config-user.nix;
       format = "qcow2";
-      diskSize = 8192;
       partitionTableType = if cfg.efi then "efi" else "legacy";
     };
 
diff --git a/nixos/modules/virtualisation/oci-options.nix b/nixos/modules/virtualisation/oci-options.nix
index 0dfedc6a530c..76f3475a4281 100644
--- a/nixos/modules/virtualisation/oci-options.nix
+++ b/nixos/modules/virtualisation/oci-options.nix
@@ -9,6 +9,12 @@
           Whether the OCI instance is using EFI.
         '';
       };
+      diskSize = lib.mkOption {
+        type = lib.types.int;
+        default = 8192;
+        description = "Size of the disk image created in MB.";
+        example = "diskSize = 12 * 1024; # 12GiB";
+      };
     };
   };
 }