diff --git a/x-pack/plugins/uptime/common/runtime_types/monitor/state.ts b/x-pack/plugins/uptime/common/runtime_types/monitor/state.ts
index 90aa692f89a42..b3c39e5180adf 100644
--- a/x-pack/plugins/uptime/common/runtime_types/monitor/state.ts
+++ b/x-pack/plugins/uptime/common/runtime_types/monitor/state.ts
@@ -9,7 +9,7 @@ import * as t from 'io-ts';
 export const CheckMonitorType = t.intersection([
   t.partial({
     name: t.string,
-    ip: t.union([t.array(t.string), t.string]),
+    ip: t.union([t.array(t.union([t.string, t.null])), t.string, t.null]),
   }),
   t.type({
     status: t.string,