diff --git a/mixin-utils/utils.libsonnet b/mixin-utils/utils.libsonnet
index c0692526c..5b4f2c3c0 100644
--- a/mixin-utils/utils.libsonnet
+++ b/mixin-utils/utils.libsonnet
@@ -117,12 +117,13 @@ local g = import 'grafana-builder/grafana.libsonnet';
   // withRunbookURL - Add/Override the runbook_url annotations for all alerts inside a list of rule groups.
   // - url_format: an URL format for the runbook, the alert name will be substituted in the URL.
   // - groups: the list of rule groups containing alerts.
-  withRunbookURL(url_format, groups)::
+  // - annotation_key: the key to use for the annotation whose value will be the formatted runbook URL.
+  withRunbookURL(url_format, groups, annotation_key='runbook_url')::
     local update_rule(rule) =
       if std.objectHas(rule, 'alert')
       then rule {
         annotations+: {
-          runbook_url: url_format % rule.alert,
+          [annotation_key]: url_format % rule.alert,
         },
       }
       else rule;