diff --git a/x-pack/plugins/stack_alerts/common/build_sorted_events_query.ts b/x-pack/plugins/stack_alerts/common/build_sorted_events_query.ts
index 92425433bf81..b9a65cf1a748 100644
--- a/x-pack/plugins/stack_alerts/common/build_sorted_events_query.ts
+++ b/x-pack/plugins/stack_alerts/common/build_sorted_events_query.ts
@@ -87,7 +87,7 @@ export const buildSortedEventsQuery = ({
         ...searchQuery.body,
         search_after: [searchAfterSortId],
       },
-    };
+    } as ESSearchRequest;
   }
-  return searchQuery;
+  return searchQuery as ESSearchRequest;
 };
diff --git a/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type.ts b/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type.ts
index b8190340c4d6..a0da622a73ce 100644
--- a/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type.ts
+++ b/x-pack/plugins/stack_alerts/server/alert_types/es_query/alert_type.ts
@@ -175,7 +175,17 @@ export function getAlertType(
               {
                 bool: {
                   must_not: [
-                    { bool: { filter: [{ range: { [params.timeField]: { lte: timestamp } } }] } },
+                    {
+                      bool: {
+                        filter: [
+                          {
+                            range: {
+                              [params.timeField]: { lte: new Date(timestamp).toISOString() },
+                            },
+                          },
+                        ],
+                      },
+                    },
                   ],
                 },
               },