diff --git a/package.json b/package.json
index ed15282..5003d4a 100644
--- a/package.json
+++ b/package.json
@@ -57,6 +57,6 @@
     "registry": "https://registry.npmjs.org/"
   },
   "dependencies": {
-    "make-synchronized": "^0.2.1"
+    "make-synchronized": "^0.2.5"
   }
 }
diff --git a/readme.md b/readme.md
index e93a596..dba10dd 100644
--- a/readme.md
+++ b/readme.md
@@ -31,7 +31,7 @@ synchronizedPrettier.format("foo( )", { parser: "babel" });
 // => 'foo();\n'
 ```
 
-This package is a simple wrapper of [`make-synchronized`](https://github.com/fisker/make-synchronized), currently only the functions and primitive values exported from `prettier` is functional, functions not exported directly (eg: `prettier.__debug.parse`) doesn't work, but it can be supported, if you want more functionality, please [open an issue](https://github.com/prettier/prettier-synchronized/issues/new).
+This package is a simple wrapper of [`make-synchronized`](https://github.com/fisker/make-synchronized).
 
 For more complex use cases, it more reasonable to extract into a separate file, and run with [`make-synchronized`](https://github.com/fisker/make-synchronized), example
 
diff --git a/test.js b/test.js
index ed72a85..00c2f22 100644
--- a/test.js
+++ b/test.js
@@ -6,13 +6,18 @@ import prettier from "prettier";
 import synchronizedPrettier, { createSynchronizedPrettier } from "./index.cjs";
 import fakePrettier from "./a-fake-prettier-to-test.cjs";
 
+const code = await fs.readFile("./index.cjs", "utf8");
+
 test("format", async () => {
-  const code = await fs.readFile("./index.cjs", "utf8");
   const formatOptions = { parser: "meriyah" };
-  assert.equal(
-    synchronizedPrettier.format(code, formatOptions),
-    await prettier.format(code, formatOptions),
+  const formattedBySynchronizedPrettier = synchronizedPrettier.format(
+    code,
+    formatOptions,
   );
+  assert.equal(typeof formattedBySynchronizedPrettier, "string");
+
+  const formattedByPrettier = await prettier.format(code, formatOptions);
+  assert.equal(formattedBySynchronizedPrettier, formattedByPrettier);
 
   let error;
   try {
@@ -27,6 +32,20 @@ test("version", () => {
   assert.equal(synchronizedPrettier.version, prettier.version);
 });
 
+test("functions not exported directly", async () => {
+  const parseOptions = { parser: "meriyah" };
+  const { ast: astParsedBySynchronizedPrettier } =
+    synchronizedPrettier.__debug.parse(code, parseOptions);
+
+  assert.equal(ast.type, "Program");
+
+  const { ast: astParsedByPrettier } = await prettier.__debug.parse(
+    code,
+    parseOptions,
+  );
+  assert.deepEqual(ast, astParsedByPrettier);
+});
+
 {
   const fakePrettierRelatedPath = "./a-fake-prettier-to-test.cjs";
   const fakePrettierUrl = new URL(fakePrettierRelatedPath, import.meta.url);