diff --git a/server/src/service/infrastructure/globalPingService.ts b/server/src/service/infrastructure/globalPingService.ts
index 6050cc5eb..e261c7b19 100644
--- a/server/src/service/infrastructure/globalPingService.ts
+++ b/server/src/service/infrastructure/globalPingService.ts
@@ -1,5 +1,5 @@
 import type { GeoContinent, GeoCheckResult, GeoCheckTimings, GeoCheckLocation } from "@/types/geoCheck.js";
-import { supportsGeoCheck } from "@/types/monitor.js";
+import { supportsGeoCheck, type HttpStatusCode } from "@/types/monitor.js";
 import { MonitorType } from "@/types/index.js";
 import type { ILogger } from "@/utils/logger.js";
 import got from "got";
@@ -62,7 +62,7 @@ interface GlobalPingProbeResult {
 export interface IGlobalPingService {
 	readonly serviceName: string;
 	createMeasurement(monitorType: MonitorType, url: string, locations: GeoContinent[]): Promise<string | null>;
-	pollForResults(measurementId: string, timeoutMs?: number, customUpCodes?: number[]): Promise<GeoCheckResult[]>;
+	pollForResults(measurementId: string, timeoutMs?: number, customUpCodes?: HttpStatusCode[]): Promise<GeoCheckResult[]>;
 }
 
 export class GlobalPingService implements IGlobalPingService {
@@ -119,7 +119,11 @@ export class GlobalPingService implements IGlobalPingService {
 		}
 	}
 
-	async pollForResults(measurementId: string, timeoutMs: number = MAX_POLL_TIMEOUT_MS, customUpCodes: number[] = []): Promise<GeoCheckResult[]> {
+	async pollForResults(
+		measurementId: string,
+		timeoutMs: number = MAX_POLL_TIMEOUT_MS,
+		customUpCodes: HttpStatusCode[] = []
+	): Promise<GeoCheckResult[]> {
 		const startTime = Date.now();
 
 		while (Date.now() - startTime < timeoutMs) {
@@ -174,7 +178,7 @@ export class GlobalPingService implements IGlobalPingService {
 		return [];
 	}
 
-	private transformResults(probeResults: GlobalPingProbeResult[], customUpCodes: number[] = []): GeoCheckResult[] {
+	private transformResults(probeResults: GlobalPingProbeResult[], customUpCodes: HttpStatusCode[] = []): GeoCheckResult[] {
 		const successfulResults: GeoCheckResult[] = [];
 
 		for (const probeResult of probeResults) {
diff --git a/server/src/service/infrastructure/network/HttpProvider.ts b/server/src/service/infrastructure/network/HttpProvider.ts
index 2ae177819..971c4e6c2 100644
--- a/server/src/service/infrastructure/network/HttpProvider.ts
+++ b/server/src/service/infrastructure/network/HttpProvider.ts
@@ -31,14 +31,15 @@ export class HttpProvider implements IStatusProvider<HttpStatusPayload> {
 
 	private handleHttpError<T>(error: unknown, monitor: Monitor): MonitorStatusResponse<T> {
 		if (error instanceof HTTPError || error instanceof RequestError) {
-			const isCustomUp = error instanceof HTTPError && (monitor.customUpCodes ?? []).includes(error.response?.statusCode);
+			const statusCode = error.response?.statusCode;
+			const statusUp = statusCode !== undefined && monitor.customUpCodes.includes(statusCode);
 
 			return {
 				monitorId: monitor.id,
 				teamId: monitor.teamId,
 				type: monitor.type,
-				status: isCustomUp,
-				code: error.response?.statusCode ?? NETWORK_ERROR,
+				status: statusUp,
+				code: statusCode ?? NETWORK_ERROR,
 				message: error.message,
 				responseTime: error.timings?.phases?.total ?? 0,
 				timings: error.timings,
@@ -104,11 +105,12 @@ export class HttpProvider implements IStatusProvider<HttpStatusPayload> {
 			}
 
 			const matchResult = this.advancedMatcher.validate<T>(payload, monitor);
+			const statusUp = monitor.customUpCodes.includes(response.statusCode) || response.ok;
 			return {
 				monitorId: monitor.id,
 				teamId: monitor.teamId,
 				type: monitor.type,
-				status: ((monitor.customUpCodes ?? []).includes(response.statusCode) || response.ok) && matchResult.ok,
+				status: statusUp && matchResult.ok,
 				code: response.statusCode,
 				message: matchResult.ok ? (response.statusMessage ?? "OK") : matchResult.message,
 				responseTime: response.timings.phases.total ?? 0,
diff --git a/server/src/types/monitor.ts b/server/src/types/monitor.ts
index 415b7dff0..3c543616c 100644
--- a/server/src/types/monitor.ts
+++ b/server/src/types/monitor.ts
@@ -2,6 +2,11 @@ import type { CheckSnapshot } from "@/types/check.js";
 export type { CheckSnapshot } from "@/types/check.js";
 import type { GeoContinent, GroupedGeoCheck } from "@/types/geoCheck.js";
 export type { GeoContinent } from "@/types/geoCheck.js";
+import http from "node:http";
+
+export const HttpStatusCodes = Object.keys(http.STATUS_CODES).map(Number);
+export const HttpStatusCodeSet = new Set(HttpStatusCodes);
+export type HttpStatusCode = number;
 
 export const MonitorTypes = ["http", "ping", "pagespeed", "hardware", "docker", "port", "game", "grpc", "websocket", "dns", "unknown"] as const;
 export type MonitorType = (typeof MonitorTypes)[number];
@@ -60,7 +65,7 @@ export interface Monitor {
 	uptimePercentage?: number;
 	notifications: string[];
 	tags: string[];
-	customUpCodes: number[];
+	customUpCodes: HttpStatusCode[];
 	secret?: string;
 	cpuAlertThreshold: number;
 	cpuAlertCounter: number;
diff --git a/server/src/validation/monitorValidation.ts b/server/src/validation/monitorValidation.ts
index 22a1a241e..2d70830b7 100644
--- a/server/src/validation/monitorValidation.ts
+++ b/server/src/validation/monitorValidation.ts
@@ -1,10 +1,9 @@
 import { z } from "zod";
 import { booleanCoercion, dnsHostnameRegex, dnsServerValidation } from "./shared.js";
 import { GeoContinents } from "@/types/geoCheck.js";
-import { DnsRecordTypes, MonitorMatchMethods, MonitorStatuses, MonitorTypes, PageSpeedStrategies } from "@/types/monitor.js";
-import http from "node:http";
+import { DnsRecordTypes, HttpStatusCodeSet, MonitorMatchMethods, MonitorStatuses, MonitorTypes, PageSpeedStrategies } from "@/types/monitor.js";
 
-const httpStatusCode = z.number().refine((code) => code.toString() in http.STATUS_CODES, { message: "Must be a valid HTTP status code" });
+const httpStatusCode = z.number().refine((code) => HttpStatusCodeSet.has(code), { message: "Must be a valid HTTP status code" });
 
 export const getMonitorByIdParamValidation = z.object({
 	monitorId: z.string().min(1, "Monitor ID is required"),
diff --git a/server/test/unit/providers/network/httpProvider.test.ts b/server/test/unit/providers/network/httpProvider.test.ts
index afd3710d9..9252493e0 100644
--- a/server/test/unit/providers/network/httpProvider.test.ts
+++ b/server/test/unit/providers/network/httpProvider.test.ts
@@ -56,6 +56,7 @@ const makeMonitor = (overrides?: Partial<Monitor>): Monitor =>
 		useAdvancedMatching: false,
 		matchMethod: undefined,
 		expectedValue: undefined,
+		customUpCodes: [],
 		...overrides,
 	}) as Monitor;