diff --git a/lib/jsdom/living/xmlhttprequest.js b/lib/jsdom/living/xmlhttprequest.js
index 49781f00ee..b9a15cb14d 100644
--- a/lib/jsdom/living/xmlhttprequest.js
+++ b/lib/jsdom/living/xmlhttprequest.js
@@ -611,7 +611,7 @@ module.exports = function createXMLHttpRequest(window) {
         const res = spawnSync(
           process.execPath,
           [syncWorkerFile],
-          { input: flagStr }
+          { input: flagStr, maxBuffer: Infinity }
         );
         if (res.status !== 0) {
           throw new Error(res.stderr.toString());
diff --git a/test/web-platform-tests/run-wpts.js b/test/web-platform-tests/run-wpts.js
index fd24d9ac7a..fe8d5571bd 100644
--- a/test/web-platform-tests/run-wpts.js
+++ b/test/web-platform-tests/run-wpts.js
@@ -14,11 +14,13 @@ const validReasons = new Set([
   "flaky",
   "mutates-globals",
   "needs-node10",
-  "needs-node11"
+  "needs-node11",
+  "needs-node12"
 ]);
 
 const hasNode10 = Number(process.versions.node.split(".")[0]) >= 10;
 const hasNode11 = Number(process.versions.node.split(".")[0]) >= 11;
+const hasNode12 = Number(process.versions.node.split(".")[0]) >= 12;
 
 const manifestFilename = path.resolve(__dirname, "wpt-manifest.json");
 const manifest = readManifest(manifestFilename);
@@ -55,7 +57,8 @@ describe("web-platform-tests", () => {
           const shouldSkip = ["fail-slow", "timeout", "flaky", "mutates-globals"].includes(reason);
           const expectFail = (reason === "fail") ||
                              (reason === "needs-node10" && !hasNode10) ||
-                             (reason === "needs-node11" && !hasNode11);
+                             (reason === "needs-node11" && !hasNode11) ||
+                             (reason === "needs-node12" && !hasNode12);
 
           if (matchingPattern && shouldSkip) {
             specify.skip(`[${reason}] ${testFile}`);
diff --git a/test/web-platform-tests/to-run.yaml b/test/web-platform-tests/to-run.yaml
index 75fcb43cd0..14b3c0f8ba 100644
--- a/test/web-platform-tests/to-run.yaml
+++ b/test/web-platform-tests/to-run.yaml
@@ -28,7 +28,7 @@ basic.htm: [fail, Unknown]
 client-hint-request-headers-2.tentative.htm: [fail, Client Hints not implemented]
 client-hint-request-headers.htm: [fail-slow, Client Hints not implemented]
 cors-safelisted-request-header.any.html: [fail, Depends on fetch]
-credentials-flag.htm: [fail, Unknown]
+credentials-flag.htm: [needs-node12, Unknown]
 image-tainting-in-cross-origin-iframe.sub.html: [timeout, Unknown]
 origin.htm: [timeout, https://github.com/tmpvar/jsdom/issues/1833]
 preflight-cache.htm: [timeout, Cache should probably be implemented for simple requests before]
@@ -128,7 +128,7 @@ DIR: dom/nodes
 Comment-constructor.html: [fail, Unknown]
 DOMImplementation-createDocument.html: [fail, Unknown]
 Document-URL.html: [fail, Unknown]
-Document-characterSet-normalization.html: [fail, Some encodings are not supported - see the whatwg-encoding module]
+Document-characterSet-normalization.html: [timeout, Some encodings are not supported - see the whatwg-encoding module]
 Document-constructor-svg.svg: [fail, Unknown]
 Document-constructor-xml.xml: [fail, Unknown]
 Document-constructor.html: [fail, new Document().origin should inherit from current Document]
@@ -980,6 +980,7 @@ open-url-worker-origin.htm: [fail, Needs Worker implementation]
 open-url-worker-simple.htm: [timeout, Needs Worker implementation]
 overridemimetype-blob.html: [fail, Unknown]
 overridemimetype-edge-cases.window.html: [fail, Unknown]
+response-method.htm: [flaky, Usually fails with a Parse Error in Node.js v12, but occasionally passes as it did in previous versions]
 responseType-document-in-worker.html: [fail, Needs Worker implementation]
 responseXML-unavailable-in-worker.html: [fail, Needs Worker implementation]
 responsedocument-decoding.htm: [fail, Unknown]