diff --git a/docker_nix/action.yml b/docker_nix/action.yml
index 72f0374..ae60f60 100644
--- a/docker_nix/action.yml
+++ b/docker_nix/action.yml
@@ -1,5 +1,10 @@
 name: 'Get image ready to run nix jobs'
 description: 'Update apt repositories and installing sudo'
+inputs:
+  nix_version:
+    description: 'Nix version to be installed'
+    required: false
+    default: nixos-unstable
 runs:
   using: 'composite'
   steps: