diff --git a/modules/docker-ci-runner/default.nix b/modules/docker-ci-runner/default.nix
index be7ecc4..11998fd 100644
--- a/modules/docker-ci-runner/default.nix
+++ b/modules/docker-ci-runner/default.nix
@@ -57,6 +57,7 @@ in
       description = ''
         Location of nix cache that is shared between builds
       '';
+      default = "/var/lib/docker-ci-runner";
       type = types.path;
     };