diff --git a/test/tests/attachmentsTest.js b/test/tests/attachmentsTest.js
index 8b80f3bf9a..2e4bf3949d 100644
--- a/test/tests/attachmentsTest.js
+++ b/test/tests/attachmentsTest.js
@@ -329,7 +329,7 @@ describe("Zotero.Attachments", function() {
 		Components.utils.import("resource://zotero-unit/httpd.js");
 		var testServerPath, httpd, prefix;
 		var testServerPortMin = 16213;
-		var testServerPortMax = testServerPort + 50;
+		var testServerPortMax = testServerPortMin + 20;
 		var testServerPort = testServerPortMin;
 
 		before(async function () {
diff --git a/test/tests/zoteroPaneTest.js b/test/tests/zoteroPaneTest.js
index daef9da17c..b2b9f4a942 100644
--- a/test/tests/zoteroPaneTest.js
+++ b/test/tests/zoteroPaneTest.js
@@ -144,7 +144,7 @@ describe("ZoteroPane", function() {
 		Components.utils.import("resource://zotero-unit/httpd.js");
 		var apiKey = Zotero.Utilities.randomString(24);
 		var testServerPortMin = 16213;
-		var testServerPortMax = testServerPort + 20;
+		var testServerPortMax = testServerPortMin + 20;
 		var testServerPort = testServerPortMin;
 		var baseURL;
 		var httpd;