diff --git a/x-pack/plugins/observability_solution/observability/server/lib/rules/custom_threshold/utils.ts b/x-pack/plugins/observability_solution/observability/server/lib/rules/custom_threshold/utils.ts
index 74f6089af312f..ca9b378d74eaa 100644
--- a/x-pack/plugins/observability_solution/observability/server/lib/rules/custom_threshold/utils.ts
+++ b/x-pack/plugins/observability_solution/observability/server/lib/rules/custom_threshold/utils.ts
@@ -59,7 +59,8 @@ export const validateKQLStringFilter = (value: string) => {
     });
   } catch (e) {
     return i18n.translate('xpack.observability.customThreshold.rule.schema.invalidFilterQuery', {
-      defaultMessage: `filterQuery must be a valid KQL filter (error: ${e.message})`,
+      defaultMessage: 'filterQuery must be a valid KQL filter (error: {errorMessage})',
+      values: { errorMessage: e?.message },
     });
   }
 };