diff --git a/nixos/modules/services/monitoring/prometheus/alertmanager.nix b/nixos/modules/services/monitoring/prometheus/alertmanager.nix
index 8706a18a184d..0c0931d3d295 100644
--- a/nixos/modules/services/monitoring/prometheus/alertmanager.nix
+++ b/nixos/modules/services/monitoring/prometheus/alertmanager.nix
@@ -34,7 +34,7 @@ in {
     (mkRemovedOptionModule [ "services" "prometheus" "alertmanager" "group" ] "The alertmanager service is now using systemd's DynamicUser mechanism which obviates a group setting.")
     (mkRemovedOptionModule [ "services" "prometheus" "alertmanagerURL" ] ''
       Due to incompatibility, the alertmanagerURL option has been removed,
-      please use 'services.prometheus2.alertmanagers' instead.
+      please use 'services.prometheus.alertmanagers' instead.
     '')
   ];