diff --git a/flake.nix b/flake.nix
index 5c77ea39..043087a1 100644
--- a/flake.nix
+++ b/flake.nix
@@ -598,6 +598,7 @@
             alert2muc.nixosModules.default
             ./hosts/prometheus
           ];
+          nixos = inputs.nixos-23-05;
         };
 
         pulsebert = nixosSystem' {