diff --git a/testing/web-platform/tests/url/urlsearchparams-constructor.any.js b/testing/web-platform/tests/url/urlsearchparams-constructor.any.js
index f7989f70ea00..8d855a4fd4d0 100644
--- a/testing/web-platform/tests/url/urlsearchparams-constructor.any.js
+++ b/testing/web-platform/tests/url/urlsearchparams-constructor.any.js
@@ -73,6 +73,23 @@ test(function() {
     assert_false(seed.has('g'));
 }, 'URLSearchParams constructor, object.');
 
+test(function() {
+    var formData = new FormData()
+    formData.append('a', 'b')
+    formData.append('c', 'd')
+    var params = new URLSearchParams(formData);
+    assert_true(params != null, 'constructor returned non-null value.');
+    assert_equals(params.get('a'), 'b');
+    assert_equals(params.get('c'), 'd');
+    assert_false(params.has('d'));
+    // The name-value pairs are copied when created; later updates
+    // should not be observable.
+    formData.append('e', 'f');
+    assert_false(params.has('e'));
+    params.append('g', 'h');
+    assert_false(formData.has('g'));
+}, 'URLSearchParams constructor, FormData.');
+
 test(function() {
     var params = new URLSearchParams('a=b+c');
     assert_equals(params.get('a'), 'b c');