diff --git a/chrome/content/zotero/HiddenBrowser.jsm b/chrome/content/zotero/HiddenBrowser.jsm
index 6d841911cc..5fbc2447ea 100644
--- a/chrome/content/zotero/HiddenBrowser.jsm
+++ b/chrome/content/zotero/HiddenBrowser.jsm
@@ -62,6 +62,7 @@ const HiddenBrowser = {
 	 * @param {Boolean} [options.allowJavaScript]
 	 * @param {Object} [options.docShell] Fields to set on Browser.docShell
 	 * @param {Boolean} [options.requireSuccessfulStatus]
+	 * @param {Boolean} [options.blockRemoteResources] Block all remote (non-file:) resources
 	 * @param {Zotero.CookieSandbox} [options.cookieSandbox]
 	 */
 	async create(source, options = {}) {
@@ -108,6 +109,10 @@ const HiddenBrowser = {
 			}, 1000 * 60);
 		}
 		
+		if (options.blockRemoteResources) {
+			RemoteResourceBlockingObserver.watch(browser);
+		}
+		
 		// Next bit adapted from Mozilla's HeadlessShell.jsm
 		const principal = Services.scriptSecurityManager.getSystemPrincipal();
 		try {
@@ -229,9 +234,43 @@ const HiddenBrowser = {
 	destroy(browser) {
 		var frame = browserFrameMap.get(browser);
 		if (frame) {
+			RemoteResourceBlockingObserver.unwatch(browser);
 			frame.destroy();
 			Zotero.debug("Deleted hidden browser");
 			browserFrameMap.delete(browser);
 		}
 	}
 };
+
+const RemoteResourceBlockingObserver = {
+	_observerAdded: false,
+	_ids: new Set(),
+	
+	observe(subject) {
+		let channel = subject.QueryInterface(Ci.nsIHttpChannel);
+		let id = Zotero.platformMajorVersion > 102 ? channel.browserId : channel.topBrowsingContextId;
+		if (this._ids.has(id) && channel.URI.scheme !== 'file') {
+			channel.cancel(Cr.NS_BINDING_ABORTED);
+		}
+	},
+	
+	watch(browser) {
+		let id = Zotero.platformMajorVersion > 102 ? browser.browserId : browser.browsingContext.id;
+		this._ids.add(id);
+		if (!this._observerAdded) {
+			Services.obs.addObserver(this, 'http-on-modify-request');
+			Zotero.debug('RemoteResourceBlockingObserver: Added observer');
+			this._observerAdded = true;
+		}
+	},
+	
+	unwatch(browser) {
+		let id = Zotero.platformMajorVersion > 102 ? browser.browserId : browser.browsingContext.id;
+		this._ids.delete(id);
+		if (this._observerAdded && !this._ids.size) {
+			Services.obs.removeObserver(this, 'http-on-modify-request');
+			Zotero.debug('RemoteResourceBlockingObserver: Removed observer');
+			this._observerAdded = false;
+		}
+	}
+};
diff --git a/chrome/content/zotero/xpcom/fulltext.js b/chrome/content/zotero/xpcom/fulltext.js
index 2550105b24..a37a805b03 100644
--- a/chrome/content/zotero/xpcom/fulltext.js
+++ b/chrome/content/zotero/xpcom/fulltext.js
@@ -1541,7 +1541,7 @@ Zotero.Fulltext = Zotero.FullText = new function(){
 		var pageData;
 		try {
 			let url = Zotero.File.pathToFileURI(path);
-			browser = await HiddenBrowser.create(url);
+			browser = await HiddenBrowser.create(url, { blockRemoteResources: true });
 			pageData = await HiddenBrowser.getPageData(browser, ['characterSet', 'bodyText']);
 		}
 		finally {
diff --git a/test/tests/HiddenBrowserTest.js b/test/tests/HiddenBrowserTest.js
index d47a79ba12..07b473853c 100644
--- a/test/tests/HiddenBrowserTest.js
+++ b/test/tests/HiddenBrowserTest.js
@@ -7,12 +7,30 @@ describe("HiddenBrowser", function() {
 		var httpd;
 		var port = 16213;
 		var baseURL = `http://127.0.0.1:${port}/`;
+		
+		var pngRequested = false;
 
 		before(function () {
 			Cu.import("resource://zotero-unit/httpd.js");
 			httpd = new HttpServer();
 			httpd.start(port);
 		});
+		
+		beforeEach(async function () {
+			pngRequested = false;
+			httpd.registerPathHandler(
+				'/remote.png',
+				{
+					handle: function (request, response) {
+						Zotero.debug('Something loaded the image')
+						response.setHeader('Content-Type', 'image/png', false);
+						response.setStatusLine(null, 200, 'OK');
+						response.write('');
+						pngRequested = true;
+					}
+				}
+			);
+		});
 
 		after(async function () {
 			await new Promise(resolve => httpd.stop(resolve));
@@ -22,6 +40,22 @@ describe("HiddenBrowser", function() {
 			let e = await getPromiseError(HiddenBrowser.create(baseURL + 'nonexistent', { requireSuccessfulStatus: true }));
 			assert.instanceOf(e, Zotero.HTTP.UnexpectedStatusException);
 		});
+		
+		it("should prevent a remote request with blockRemoteResources", async function () {
+			let path = OS.Path.join(getTestDataDirectory().path, 'test-hidden.html');
+			let browser = await HiddenBrowser.create(path, { blockRemoteResources: true });
+			await HiddenBrowser.getPageData(browser, ['characterSet', 'bodyText']);
+			HiddenBrowser.destroy(browser);
+			assert.isFalse(pngRequested);
+		});
+
+		it("should allow a remote request without blockRemoteResources", async function () {
+			let path = OS.Path.join(getTestDataDirectory().path, 'test-hidden.html');
+			let browser = await HiddenBrowser.create(path, { blockRemoteResources: false });
+			await HiddenBrowser.getPageData(browser, ['characterSet', 'bodyText']);
+			HiddenBrowser.destroy(browser);
+			assert.isTrue(pngRequested);
+		});
 	});
 	
 	describe("#getPageData()", function () {
diff --git a/test/tests/data/test-hidden.html b/test/tests/data/test-hidden.html
index 5fbad3f92e..1f8fc495c4 100644
--- a/test/tests/data/test-hidden.html
+++ b/test/tests/data/test-hidden.html
@@ -3,6 +3,7 @@
 		<meta charset="utf-8"/>
 	</head>
 	<body>
+		<img src="http://127.0.0.1:16213/remote.png">
 		<p>This is a test.</p>
 		<p style="display: none">This is hidden text.</p>
 	</body>