diff --git a/lib/index.js b/lib/index.js
index 3797245..fdefaae 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -21,59 +21,6 @@ exports.OM_SYRINX_VERSION = OM_SYRINX_VERSION;
 
 const { setTimeout } = require("node:timers/promises");
 
-class SyrinxStream extends Readable {
-  /**
-   * @param {import("./native").Syrinx} syrinx
-   * @param {boolean} objectMode
-   * @param {string} inputText
-   * @param {import("./native").SynthesisOption} option
-   */
-  constructor(syrinx, objectMode, inputText, option) {
-    super({ objectMode });
-    /**
-     * @type {import("./native").Syrinx}
-     * @private
-     */
-    this._syrinx = syrinx;
-    /**
-     * @type {string}
-     * @private
-     */
-    this._inputText = inputText;
-    /**
-     * @type {import("./native").SynthesisOption}
-     * @private
-     */
-    this._option = option;
-  }
-
-  /**
-   * @param {(error?: Error | null) => void} callback
-   */
-  async _construct(callback) {
-    /** @type {[import("./native").PreparedSynthesizer, null] | [null, Error]} */
-    const [synthesizer, error] = await this._syrinx
-      .prepare(this._inputText, this._option)
-      .then(
-        (s) => [s, null],
-        (e) => [null, e],
-      );
-    callback(error);
-
-    await synthesizer?.synthesize((err, result) => {
-      if (err) this.emit("error", err);
-      else this.push(result);
-    });
-
-    // The last push sometimes occurs after the Promise resolution,
-    // so we need to make sure that the last push occurs before the stream ends.
-    await setTimeout();
-    this.push(null);
-  }
-
-  _read() {}
-}
-
 class Syrinx {
   /**
    * @param {import("./native").SyrinxConfig} config
@@ -117,7 +64,37 @@ class Syrinx {
    * @returns {Readable}
    */
   synthesize(inputText, option) {
-    return new SyrinxStream(this._inner, this._objectMode, inputText, option);
+    const { _inner } = this;
+
+    return new Readable({
+      objectMode: this._objectMode,
+
+      /**
+       * @param {(error?: Error | null) => void} callback
+       */
+      async construct(callback) {
+        /** @type {[import("./native").PreparedSynthesizer, null] | [null, Error]} */
+        const [synthesizer, error] = await _inner
+          .prepare(inputText, option)
+          .then(
+            (s) => [s, null],
+            (e) => [null, e],
+          );
+        callback(error);
+
+        await synthesizer?.synthesize((err, result) => {
+          if (err) this.emit("error", err);
+          else this.push(result);
+        });
+
+        // The last push sometimes occurs after the Promise resolution,
+        // so we need to make sure that the last push occurs before the stream ends.
+        await setTimeout();
+        this.push(null);
+      },
+
+      read() {},
+    });
   }
 }