diff --git a/cli/dts/lib.deno.ns.d.ts b/cli/dts/lib.deno.ns.d.ts
index 46b4bda712..92eaffc765 100644
--- a/cli/dts/lib.deno.ns.d.ts
+++ b/cli/dts/lib.deno.ns.d.ts
@@ -85,6 +85,7 @@ declare namespace Deno {
     export class BadResource extends Error {}
     export class Http extends Error {}
     export class Busy extends Error {}
+    export class NotSupported extends Error {}
   }
 
   /** The current process id of the runtime. */
diff --git a/cli/tests/unit/error_test.ts b/cli/tests/unit/error_test.ts
new file mode 100644
index 0000000000..444b0445ac
--- /dev/null
+++ b/cli/tests/unit/error_test.ts
@@ -0,0 +1,24 @@
+// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.
+import { assert } from "./test_util.ts";
+
+Deno.test("Errors work", () => {
+  assert(new Deno.errors.NotFound("msg") instanceof Error);
+  assert(new Deno.errors.PermissionDenied("msg") instanceof Error);
+  assert(new Deno.errors.ConnectionRefused("msg") instanceof Error);
+  assert(new Deno.errors.ConnectionReset("msg") instanceof Error);
+  assert(new Deno.errors.ConnectionAborted("msg") instanceof Error);
+  assert(new Deno.errors.NotConnected("msg") instanceof Error);
+  assert(new Deno.errors.AddrInUse("msg") instanceof Error);
+  assert(new Deno.errors.AddrNotAvailable("msg") instanceof Error);
+  assert(new Deno.errors.BrokenPipe("msg") instanceof Error);
+  assert(new Deno.errors.AlreadyExists("msg") instanceof Error);
+  assert(new Deno.errors.InvalidData("msg") instanceof Error);
+  assert(new Deno.errors.TimedOut("msg") instanceof Error);
+  assert(new Deno.errors.Interrupted("msg") instanceof Error);
+  assert(new Deno.errors.WriteZero("msg") instanceof Error);
+  assert(new Deno.errors.UnexpectedEof("msg") instanceof Error);
+  assert(new Deno.errors.BadResource("msg") instanceof Error);
+  assert(new Deno.errors.Http("msg") instanceof Error);
+  assert(new Deno.errors.Busy("msg") instanceof Error);
+  assert(new Deno.errors.NotSupported("msg") instanceof Error);
+});