diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index e6cd5468e98..fcacb4cedad 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -4453,7 +4453,7 @@ impl DocumentMethods for Document {
     // https://html.spec.whatwg.org/multipage/#dom-document-open-window
     fn Open_(
         &self,
-        url: DOMString,
+        url: USVString,
         target: DOMString,
         features: DOMString,
     ) -> Fallible<DomRoot<WindowProxy>> {
diff --git a/components/script/dom/webidls/Document.webidl b/components/script/dom/webidls/Document.webidl
index ebcdea32166..04e5b851c3f 100644
--- a/components/script/dom/webidls/Document.webidl
+++ b/components/script/dom/webidls/Document.webidl
@@ -122,7 +122,7 @@ partial /*sealed*/ interface Document {
   [CEReactions, Throws]
   Document open(optional DOMString unused1, optional DOMString unused2);
   [CEReactions, Throws]
-  WindowProxy open(DOMString url, DOMString name, DOMString features);
+  WindowProxy open(USVString url, DOMString name, DOMString features);
   [CEReactions, Throws]
   void close();
   [CEReactions, Throws]
diff --git a/components/script/dom/webidls/Window.webidl b/components/script/dom/webidls/Window.webidl
index 56d9d06a819..28937d06e6c 100644
--- a/components/script/dom/webidls/Window.webidl
+++ b/components/script/dom/webidls/Window.webidl
@@ -40,7 +40,7 @@
   // https://github.com/whatwg/html/issues/2115
   [Replaceable] readonly attribute WindowProxy? parent;
   readonly attribute Element? frameElement;
-  WindowProxy? open(optional DOMString url = "about:blank", optional DOMString target = "_blank",
+  WindowProxy? open(optional USVString url = "", optional DOMString target = "_blank",
                     optional DOMString features = "");
   //getter WindowProxy (unsigned long index);
 
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 09247103d0c..933799dc067 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -616,7 +616,7 @@ impl WindowMethods for Window {
     // https://html.spec.whatwg.org/multipage/#dom-open
     fn Open(
         &self,
-        url: DOMString,
+        url: USVString,
         target: DOMString,
         features: DOMString,
     ) -> Option<DomRoot<WindowProxy>> {
diff --git a/components/script/dom/windowproxy.rs b/components/script/dom/windowproxy.rs
index d64975a78b9..3ff326c683a 100644
--- a/components/script/dom/windowproxy.rs
+++ b/components/script/dom/windowproxy.rs
@@ -10,7 +10,7 @@ use crate::dom::bindings::inheritance::Castable;
 use crate::dom::bindings::proxyhandler::fill_property_descriptor;
 use crate::dom::bindings::reflector::{DomObject, Reflector};
 use crate::dom::bindings::root::{Dom, DomRoot};
-use crate::dom::bindings::str::DOMString;
+use crate::dom::bindings::str::{DOMString, USVString};
 use crate::dom::bindings::trace::JSTraceable;
 use crate::dom::bindings::utils::{get_array_index_from_id, AsVoidPtr, WindowProxyHandler};
 use crate::dom::dissimilaroriginwindow::DissimilarOriginWindow;
@@ -395,7 +395,7 @@ impl WindowProxy {
     // https://html.spec.whatwg.org/multipage/#window-open-steps
     pub fn open(
         &self,
-        url: DOMString,
+        url: USVString,
         target: DOMString,
         features: DOMString,
     ) -> Option<DomRoot<WindowProxy>> {
diff --git a/tests/wpt/metadata/fetch/security/embedded-credentials.tentative.sub.html.ini b/tests/wpt/metadata/fetch/security/embedded-credentials.tentative.sub.html.ini
index f5118b7d9f5..35196e2d082 100644
--- a/tests/wpt/metadata/fetch/security/embedded-credentials.tentative.sub.html.ini
+++ b/tests/wpt/metadata/fetch/security/embedded-credentials.tentative.sub.html.ini
@@ -1,6 +1,5 @@
 [embedded-credentials.tentative.sub.html]
   type: testharness
-  expected: TIMEOUT
   [Embedded credentials are treated as network errors.]
     expected: FAIL
 
@@ -11,11 +10,11 @@
     expected: FAIL
 
   [Embedded credentials matching the top-level are not treated as network errors for relative URLs.]
-    expected: TIMEOUT
+    expected: FAIL
 
   [Embedded credentials matching the top-level are not treated as network errors for same-origin URLs.]
-    expected: TIMEOUT
+    expected: FAIL
 
   [Embedded credentials matching the top-level are treated as network errors for cross-origin URLs.]
-    expected: TIMEOUT
+    expected: FAIL
 
diff --git a/tests/wpt/metadata/html/browsers/the-window-object/window-open-defaults.window.js.ini b/tests/wpt/metadata/html/browsers/the-window-object/window-open-defaults.window.js.ini
deleted file mode 100644
index 8e1733fed8b..00000000000
--- a/tests/wpt/metadata/html/browsers/the-window-object/window-open-defaults.window.js.ini
+++ /dev/null
@@ -1,4 +0,0 @@
-[window-open-defaults.window.html]
-  [window.open()'s url parameter default]
-    expected: FAIL
-