diff --git a/packages/controller/src/Controller.ts b/packages/controller/src/Controller.ts
index 6d2c0426..75a0e084 100644
--- a/packages/controller/src/Controller.ts
+++ b/packages/controller/src/Controller.ts
@@ -842,7 +842,7 @@ export default class Controller {
 		try {
 			manifest = JSON.parse(await fs.readFile(filePath, { encoding: "utf8" }));
 		} catch (err: any) {
-			if (throwOnMissing && err.code !== "ENOENT") {
+			if (throwOnMissing || err.code !== "ENOENT") {
 				throw err;
 			}
 		}
diff --git a/test/controller/Controller.js b/test/controller/Controller.js
index c0fc29e6..efcc69ee 100644
--- a/test/controller/Controller.js
+++ b/test/controller/Controller.js
@@ -1,3 +1,5 @@
+import fs from "node:fs/promises";
+import os from "node:os";
 import path from "node:path";
 import assert from "node:assert/strict";
 import { Controller, HostRecord, InstanceRecord, UserRecord } from "@clusterio/controller";
@@ -55,6 +57,35 @@ describe("controller/src/Controller", function() {
 				assert(list.check(ip), `${ip} missing from list`);
 			}
 		}
+		describe(".loadJsonObject()", function() {
+			let dir;
+			before(async function() {
+				dir = await fs.mkdtemp(path.join(os.tmpdir(), "clusterio-load-json-"));
+				await fs.writeFile(path.join(dir, "valid.json"), JSON.stringify({ "main.js": "main.123.js" }));
+				await fs.writeFile(path.join(dir, "invalid.json"), "{ not json");
+			});
+			after(async function() {
+				await fs.rm(dir, { recursive: true, force: true });
+			});
+			it("should parse an existing file", async function() {
+				assert.deepEqual(
+					await Controller.loadJsonObject(path.join(dir, "valid.json")),
+					{ "main.js": "main.123.js" },
+				);
+			});
+			it("should return an empty object for a missing file by default", async function() {
+				assert.deepEqual(await Controller.loadJsonObject(path.join(dir, "missing.json")), {});
+			});
+			it("should throw for a missing file when throwOnMissing is set", async function() {
+				await assert.rejects(
+					Controller.loadJsonObject(path.join(dir, "missing.json"), true),
+					{ code: "ENOENT" },
+				);
+			});
+			it("should throw for invalid JSON", async function() {
+				await assert.rejects(Controller.loadJsonObject(path.join(dir, "invalid.json")), SyntaxError);
+			});
+		});
 		describe(".serveWeb()", function() {
 			let server, port;
 			before(async function() {