diff --git a/serialize-error/deno.json b/serialize-error/deno.json
new file mode 100644
index 0000000..8172823
--- /dev/null
+++ b/serialize-error/deno.json
@@ -0,0 +1,5 @@
+{
+  "imports": {
+    "serialize-error": "npm:serialize-error@^12.0.0"
+  }
+}
diff --git a/serialize-error/deno.lock b/serialize-error/deno.lock
new file mode 100644
index 0000000..832a01b
--- /dev/null
+++ b/serialize-error/deno.lock
@@ -0,0 +1,32 @@
+{
+  "version": "4",
+  "specifiers": {
+    "npm:@types/node@*": "22.5.4",
+    "npm:serialize-error@*": "12.0.0"
+  },
+  "npm": {
+    "@types/node@22.5.4": {
+      "integrity": "sha512-FDuKUJQm/ju9fT/SeX/6+gBzoPzlVCzfzmGkwKvRHQVxi4BntVbyIwf6a4Xn62mrvndLiml6z/UBXIdEVjQLXg==",
+      "dependencies": [
+        "undici-types"
+      ]
+    },
+    "serialize-error@12.0.0": {
+      "integrity": "sha512-ZYkZLAvKTKQXWuh5XpBw7CdbSzagarX39WyZ2H07CDLC5/KfsRGlIXV8d4+tfqX1M7916mRqR1QfNHSij+c9Pw==",
+      "dependencies": [
+        "type-fest"
+      ]
+    },
+    "type-fest@4.33.0": {
+      "integrity": "sha512-s6zVrxuyKbbAsSAD5ZPTB77q4YIdRctkTbJ2/Dqlinwz+8ooH2gd+YA7VA6Pa93KML9GockVvoxjZ2vHP+mu8g=="
+    },
+    "undici-types@6.19.8": {
+      "integrity": "sha512-ve2KP6f/JnbPBFyobGHuerC9g1FYGn/F8n1LWTwNxCEzd6IfqTwUQcNXgEtmmQ6DlRrC1hrSrBnCZPokRrDHjw=="
+    }
+  },
+  "workspace": {
+    "dependencies": [
+      "npm:serialize-error@12"
+    ]
+  }
+}
diff --git a/serialize-error/main.ts b/serialize-error/main.ts
new file mode 100644
index 0000000..cbff747
--- /dev/null
+++ b/serialize-error/main.ts
@@ -0,0 +1,7 @@
+import { addKnownErrorConstructor } from "npm:serialize-error";
+
+export class E extends Error {
+  code = "ERR";
+}
+
+addKnownErrorConstructor(E);
diff --git a/serialize-error/test.ts b/serialize-error/test.ts
new file mode 100644
index 0000000..fe96b1b
--- /dev/null
+++ b/serialize-error/test.ts
@@ -0,0 +1,13 @@
+import assert from "node:assert";
+import { deserializeError, serializeError } from "npm:serialize-error";
+import { E } from "./main.ts";
+
+Deno.test("serializeError", () => {
+  const e = serializeError(new E());
+  assert(e.code === "ERR");
+  assert(e.stack?.match(/^Error\n/));
+});
+
+Deno.test("deserializeError", () => {
+  assert(deserializeError({ name: "E", message: "🦄" }) instanceof E);
+});