diff --git a/services/monitoring/lgtm/alerts/forkos.yaml b/services/monitoring/lgtm/alerts/forkos.yaml
index e6dc3f6..013487e 100644
--- a/services/monitoring/lgtm/alerts/forkos.yaml
+++ b/services/monitoring/lgtm/alerts/forkos.yaml
@@ -1,4 +1,3 @@
-namespace: forkos
 groups:
     - name: ForkOS automation
       rules:
diff --git a/services/monitoring/lgtm/alerts/postgres.yml b/services/monitoring/lgtm/alerts/postgres.yml
index c9a229e..41e9b15 100644
--- a/services/monitoring/lgtm/alerts/postgres.yml
+++ b/services/monitoring/lgtm/alerts/postgres.yml
@@ -1,4 +1,3 @@
-namespace: postgres
 groups:
     - name: PostgreSQL
       rules:
diff --git a/services/monitoring/lgtm/alerts/resources.yaml b/services/monitoring/lgtm/alerts/resources.yaml
index 84b52cf..03aa686 100644
--- a/services/monitoring/lgtm/alerts/resources.yaml
+++ b/services/monitoring/lgtm/alerts/resources.yaml
@@ -1,4 +1,3 @@
-namespace: resources
 groups:
     - name: Host & hardware
       rules:
diff --git a/services/monitoring/lgtm/mimir.nix b/services/monitoring/lgtm/mimir.nix
index 782832f..bca3cf5 100644
--- a/services/monitoring/lgtm/mimir.nix
+++ b/services/monitoring/lgtm/mimir.nix
@@ -12,14 +12,11 @@ let
 
   alerts = pkgs.runCommand "mimir-alerts-checked" {
     src = ./alerts;
-    nativeBuildInputs = with pkgs; [ mimir ];
+    nativeBuildInputs = with pkgs; [ prometheus.cli ];
   } ''
+    promtool check rules $src/*
     mkdir $out
     cp -R $src $out/anonymous/
-    chmod -R +w $out
-    mimirtool rules check --rule-dirs=$out/anonymous
-    mimirtool rules lint --rule-dirs=$out/anonymous
-    diff -r $src $out/anonymous
   '';
 in
 {