diff --git a/packages/util/src/FlexibleBuffer.ts b/packages/util/src/FlexibleBuffer.ts
index 9c47ed0d..afa13b5d 100644
--- a/packages/util/src/FlexibleBuffer.ts
+++ b/packages/util/src/FlexibleBuffer.ts
@@ -1,42 +1,40 @@
+type IBufferRawData = number[]
+
 interface IBufferJson {
   type: string
-  data: number[]
+  data: IBufferRawData
 }
 
 interface IFlexibleBuffer {
   readonly length: number
-  push(value: ArrayLike<number>): this
+  push(value: ArrayLike<number>): void
   toBuffer(): Buffer
-  toArray(): number[]
+  toArray(): IBufferRawData
   clear(): void
   toJSON(): IBufferJson
 }
 
 export abstract class FlexibleBuffer implements IFlexibleBuffer {
   static auto(size?: number | null): FlexibleBuffer {
-    return typeof size === "number"
+    return typeof size === "number" && !isNaN(size)
       ? new BufferFlexibleBuffer(size)
       : new ArrayFlexibleBuffer();
   }
 
-  static flexible(): FlexibleBuffer {
-    return new ArrayFlexibleBuffer();
-  }
+  static flexible(): FlexibleBuffer { return new ArrayFlexibleBuffer(); }
 
-  static fixed(size: number): FlexibleBuffer {
-    return new BufferFlexibleBuffer(size);
-  }
+  static fixed(size: number): FlexibleBuffer { return new BufferFlexibleBuffer(size); }
 
   abstract readonly length: number
-  abstract push(value: ArrayLike<number>): this
+  abstract push(value: ArrayLike<number>): void
   abstract toBuffer(): Buffer
-  abstract toArray(): number[]
+  abstract toArray(): IBufferRawData
   abstract clear(): void
   abstract toJSON(): IBufferJson
 }
 
 class BufferFlexibleBuffer extends FlexibleBuffer {
-  constructor(size: number) {
+  constructor(readonly size: number) {
     super();
     this._buffer = Buffer.alloc(size);
   }
@@ -48,18 +46,17 @@ class BufferFlexibleBuffer extends FlexibleBuffer {
     return this._index;
   }
 
-  push(value: ArrayLike<number>): this {
+  push(value: ArrayLike<number>) {
     this._buffer.set(value, this._index);
     this._index += value.length;
-    return this;
   }
 
   toBuffer(): Buffer {
     return this._buffer;
   }
 
-  toArray(): number[] {
-    return Array.from(this._buffer);
+  toArray(): IBufferRawData {
+    return this.toJSON().data;
   }
 
   clear(): void {
@@ -73,29 +70,28 @@ class BufferFlexibleBuffer extends FlexibleBuffer {
 }
 
 class ArrayFlexibleBuffer extends FlexibleBuffer {
-  private readonly _buffer: any[] = [];
+  private readonly _array: Uint8Array[] = [];
   private _length = 0;
 
   get length(): number {
     return this._length;
   }
 
-  push(value: ArrayLike<number>): this {
-    this._buffer.push(value);
+  push(value: ArrayLike<number>): void {
+    this._array.push(new Uint8Array(value));
     this._length += value.length;
-    return this;
   }
 
   toBuffer(): Buffer {
-    return Buffer.concat(this._buffer);
+    return Buffer.concat(this._array, this._length);
   }
 
-  toArray(): number[] {
-    return this._buffer;
+  toArray(): IBufferRawData {
+    return this.toJSON().data;
   }
 
   clear(): void {
-    this._buffer.length = 0;
+    this._array.length = 0;
     this._length = 0;
   }
 
diff --git a/packages/util/src/test/FlexibleBuffer.test.ts b/packages/util/src/test/FlexibleBuffer.test.ts
index 002bd6a0..3b9dbd5a 100644
--- a/packages/util/src/test/FlexibleBuffer.test.ts
+++ b/packages/util/src/test/FlexibleBuffer.test.ts
@@ -2,21 +2,46 @@ import assert from "assert";
 import test, { suite } from "node:test";
 import { FlexibleBuffer } from "../FlexibleBuffer";
 
-const array = [1, 2, 3];
+const _array = [65, 66, 67];
 
 suite("Array FlexibleBuffer", () => {
-  const buffer = FlexibleBuffer.flexible();
+  const flexibleBuffer = FlexibleBuffer.flexible();
 
   test("Allow push oversized", () => {
-    buffer.push(array);
-    assert.strictEqual(buffer.length, array.length);
+    flexibleBuffer.push(_array);
+    assert.strictEqual(flexibleBuffer.length, _array.length);
+  });
+
+  test("Transform to buffer", () => {
+    assert.doesNotThrow(() => {
+      const buffer = flexibleBuffer.toBuffer();
+
+      assert.strictEqual(buffer.length, _array.length);
+
+      for (let i = 0; i < buffer.length; i++) {
+        assert.strictEqual(buffer[i], _array[i]);
+      }
+    });
   });
 });
 
 suite("Buffer FlexibleBuffer", () => {
-  const buffer = FlexibleBuffer.fixed(1);
+  const fixedBuffer = FlexibleBuffer.fixed(3);
+
+  test("Allow pushing a list with a size within the limit", () => {
+    assert.doesNotThrow(() => fixedBuffer.push(_array));
+    assert.strictEqual(fixedBuffer.length, _array.length);
+  });
 
   test("Deny push oversized", () => {
-    assert.throws(() => buffer.push(array));
+    assert.throws(() => fixedBuffer.push(_array));
+  });
+
+  test("Transform to array", () => {
+    assert.doesNotThrow(() => {
+      const array = fixedBuffer.toArray();
+      assert.strictEqual(array.length, _array.length);
+      assert.deepStrictEqual(array, _array);
+    });
   });
 });