diff --git a/nixos/modules/services/monitoring/prometheus/default.nix b/nixos/modules/services/monitoring/prometheus/default.nix
index d85825be5057..345ed324dff1 100644
--- a/nixos/modules/services/monitoring/prometheus/default.nix
+++ b/nixos/modules/services/monitoring/prometheus/default.nix
@@ -66,7 +66,7 @@ let
     rule_files = optionals (!(cfg.enableAgentMode)) (
       map (promtoolCheck "check rules" "rules") (
         cfg.ruleFiles
-        ++ [
+        ++ optionals (builtins.length cfg.rules > 0) [
           (pkgs.writeText "prometheus.rules" (concatStringsSep "\n" cfg.rules))
         ]
       )