diff --git a/IndexedDB/bigint_value.htm b/IndexedDB/bigint_value.htm
new file mode 100644
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--- /dev/null
+++ b/IndexedDB/bigint_value.htm
@@ -0,0 +1,72 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>IndexedDB: BigInt keys and values</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="support.js"></script>
+
+<script>
+// BigInt and BigInt objects are supported in serialization, per
+// https://github.com/whatwg/html/pull/3480
+// This support allows them to be used as IndexedDB values.
+
+function value_test(value, predicate, name) {
+    async_test(t => {
+        t.step(function() {
+            assert_true(predicate(value),
+                        "Predicate should return true for the initial value.");
+        });
+
+        createdb(t).onupgradeneeded = t.step_func(e => {
+            e.target.result
+                    .createObjectStore("store")
+                    .add(value, 1);
+
+            e.target.onsuccess = t.step_func(e => {
+                e.target.result
+                        .transaction("store")
+                        .objectStore("store")
+                        .get(1)
+                        .onsuccess = t.step_func(e =>
+                {
+                    assert_true(predicate(e.target.result),
+                                "Predicate should return true for the deserialized result.");
+                    t.done();
+                });
+            });
+        });
+    }, "BigInts as values in IndexedDB - " + name);
+}
+
+value_test(1n,
+           x => x === 1n,
+           "primitive BigInt");
+value_test(Object(1n),
+           x => typeof x === 'object' &&
+                x instanceof BigInt &&
+                x.valueOf() === 1n,
+           "BigInt object");
+value_test({val: 1n},
+           x => x.val === 1n,
+           "primitive BigInt inside object");
+value_test({val: Object(1n)},
+           x => x.val.valueOf() === 1n &&
+                x.val instanceof BigInt &&
+                x.val.valueOf() === 1n,
+           "BigInt object inside object");
+
+// However, BigInt is not supported as an IndexedDB key; support
+// has been proposed in the following PR, but that change has not
+// landed at the time this patch was written
+// https://github.com/w3c/IndexedDB/pull/231
+
+function invalidKey(key, name) {
+    test(t => {
+        assert_throws("DataError", () => indexedDB.cmp(0, key));
+    }, "BigInts as keys in IndexedDB - " + name);
+}
+
+invalidKey(1n, "primitive BigInt");
+// Still an error even if the IndexedDB patch lands
+invalidKey(Object(1n), "BigInt object");
+</script>
