diff --git a/components/script/dom/url.rs b/components/script/dom/url.rs
index b8d1ae9335a..664221c4bb8 100644
--- a/components/script/dom/url.rs
+++ b/components/script/dom/url.rs
@@ -42,6 +42,10 @@ impl URL {
                            global, URLBinding::Wrap)
     }
 
+    pub fn query_pairs(&self) -> Vec<(String, String)> {
+        self.url.borrow().query_pairs().into_owned().collect()
+    }
+
     pub fn set_query_pairs(&self, pairs: &[(String, String)]) {
         let mut url = self.url.borrow_mut();
         url.query_pairs_mut().clear().extend_pairs(pairs);
diff --git a/components/script/dom/urlsearchparams.rs b/components/script/dom/urlsearchparams.rs
index d3a8c29ac3e..800cd10db88 100644
--- a/components/script/dom/urlsearchparams.rs
+++ b/components/script/dom/urlsearchparams.rs
@@ -31,7 +31,7 @@ impl URLSearchParams {
     fn new_inherited(url: Option<&URL>) -> URLSearchParams {
         URLSearchParams {
             reflector_: Reflector::new(),
-            list: DOMRefCell::new(vec![]),
+            list: DOMRefCell::new(url.map_or(Vec::new(), |url| url.query_pairs())),
             url: MutableWeakRef::new(url),
         }
     }
@@ -111,26 +111,28 @@ impl URLSearchParamsMethods for URLSearchParams {
 
     // https://url.spec.whatwg.org/#dom-urlsearchparams-set
     fn Set(&self, name: USVString, value: USVString) {
-        // Step 1.
-        let mut list = self.list.borrow_mut();
-        let mut index = None;
-        let mut i = 0;
-        list.retain(|&(ref k, _)| {
-            if index.is_none() {
-                if k == &name.0 {
-                    index = Some(i);
+        {
+            // Step 1.
+            let mut list = self.list.borrow_mut();
+            let mut index = None;
+            let mut i = 0;
+            list.retain(|&(ref k, _)| {
+                if index.is_none() {
+                    if k == &name.0 {
+                        index = Some(i);
+                    } else {
+                        i += 1;
+                    }
+                    true
                 } else {
-                    i += 1;
+                    k != &name.0
                 }
-                true
-            } else {
-                k != &name.0
-            }
-        });
-        match index {
-            Some(index) => list[index].1 = value.0,
-            None => list.push((name.0, value.0)), // Step 2.
-        };
+            });
+            match index {
+                Some(index) => list[index].1 = value.0,
+                None => list.push((name.0, value.0)), // Step 2.
+            };
+        }  // Un-borrow self.list
         // Step 3.
         self.update_steps();
     }
diff --git a/tests/wpt/metadata/url/url-constructor.html.ini b/tests/wpt/metadata/url/url-constructor.html.ini
index 80ca791b9be..fbbdefe9627 100644
--- a/tests/wpt/metadata/url/url-constructor.html.ini
+++ b/tests/wpt/metadata/url/url-constructor.html.ini
@@ -75,15 +75,6 @@
   [Parsing: <h\tt\nt\rp://h\to\ns\rt:9\t0\n0\r0/p\ta\nt\rh?q\tu\ne\rry#f\tr\na\rg> against <about:blank>]
     expected: FAIL
 
-  [URL.searchParams updating, clearing]
-    expected: FAIL
-
   [URL.searchParams and URL.search setters, update propagation]
     expected: FAIL
 
-  [Parsing: <?a=b&c=d> against <http://example.org/foo/bar>]
-    expected: FAIL
-
-  [Parsing: <??a=b&c=d> against <http://example.org/foo/bar>]
-    expected: FAIL
-