diff --git a/src/util/MMKVParser.ts b/src/util/MMKVParser.ts
index f2a7d43..29b3ed5 100644
--- a/src/util/MMKVParser.ts
+++ b/src/util/MMKVParser.ts
@@ -69,18 +69,21 @@ export class MMKVParser {
     return bytesToUTF8String(data).normalize();
   }
 
-  public readVariantString() {
+  public readOptionalString() {
     // Container [
     //   len: int,
     //   data: variant
     // ]
     const containerLen = this.readInt();
+    if (containerLen === 0) {
+      return null;
+    }
     const newOffset = this.offset + containerLen;
     const result = this.readString();
     if (newOffset !== this.offset) {
       const expected = formatHex(newOffset);
       const actual = formatHex(this.offset);
-      throw new Error(`readVariantString failed: offset does mismatch (expect: ${expected}, actual: ${actual})`);
+      throw new Error(`readVariantString failed: offset mismatch (expect: ${expected}, actual: ${actual})`);
     }
     return result;
   }
@@ -99,13 +102,15 @@ export class MMKVParser {
     const result = new Map<string, string>();
     while (!mmkv.eof) {
       const key = mmkv.readString();
-      const value = mmkv.readVariantString();
-      result.set(key, value);
+      const value = mmkv.readOptionalString();
+      if (value) {
+        result.set(key, value);
+      }
     }
     return result;
   }
 
-  public static parseKuwoEKey(view: DataView) {
+  public static parseKuwoEKey(view: DataView): Omit<StagingKWMv2Key, 'id'>[] {
     const mmkv = new MMKVParser(view);
     const result: Omit<StagingKWMv2Key, 'id'>[] = [];
     while (!mmkv.eof) {
@@ -117,8 +122,10 @@ export class MMKVParser {
       }
 
       const [_, rid, quality] = idMatch;
-      const ekey = mmkv.readVariantString();
-      result.push({ rid, quality, ekey });
+      const ekey = mmkv.readOptionalString();
+      if (ekey) {
+        result.push({ rid, quality, ekey });
+      }
     }
     return result;
   }
diff --git a/src/util/__tests__/MMKVParser.test.ts b/src/util/__tests__/MMKVParser.test.ts
index e4eebcb..dc996ac 100644
--- a/src/util/__tests__/MMKVParser.test.ts
+++ b/src/util/__tests__/MMKVParser.test.ts
@@ -1,19 +1,46 @@
 import { MMKVParser } from '../MMKVParser';
 import { readFileSync } from 'node:fs';
 
-test('parse mmkv file as expected', () => {
-  const buff = readFileSync(__dirname + '/__fixture__/test.mmkv');
-  const view = new DataView(buff.buffer.slice(buff.byteOffset, buff.byteOffset + buff.byteLength));
-  expect(MMKVParser.toStringMap(view)).toEqual(
-    new Map([
-      ['key', 'value'],
-      [
-        'Lorem Ipsum',
-        'Lorem ipsum dolor sit amet, consectetur adipiscing elit. ' +
-          'Vestibulum congue volutpat metus non molestie. Quisque id est sapien. ' +
-          'Fusce eget tristique sem. Donec tellus lacus, viverra sed lectus eget, elementum ultrices dolor. ' +
-          'Integer non urna justo.',
-      ],
-    ])
-  );
+const makeViewFromBuffer = (buff: Buffer) =>
+  new DataView(buff.buffer.slice(buff.byteOffset, buff.byteOffset + buff.byteLength));
+
+test('parse qm mmkv file', () => {
+  const view = makeViewFromBuffer(readFileSync(__dirname + '/__fixture__/qm.mmkv'));
+  expect(Object.fromEntries(MMKVParser.toStringMap(view).entries())).toMatchInlineSnapshot(`
+    {
+      "Lorem Ipsum": "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum congue volutpat metus non molestie. Quisque id est sapien. Fusce eget tristique sem. Donec tellus lacus, viverra sed lectus eget, elementum ultrices dolor. Integer non urna justo.",
+      "key": "value",
+    }
+  `);
+});
+
+test('parse qm mmkv file with optional str', () => {
+  const view = makeViewFromBuffer(readFileSync(__dirname + '/__fixture__/qm_optional.mmkv'));
+  expect(Object.fromEntries(MMKVParser.toStringMap(view).entries())).toMatchInlineSnapshot(`
+    {
+      "key": "value",
+      "key2": "value2",
+    }
+  `);
+});
+
+test('parse kuwo mmkv file', () => {
+  const view = makeViewFromBuffer(readFileSync(__dirname + '/__fixture__/kuwo.mmkv'));
+  expect(MMKVParser.parseKuwoEKey(view)).toMatchInlineSnapshot(`
+    [
+      {
+        "ekey": "xyz123",
+        "quality": "20201kmflac",
+        "rid": "1234567",
+      },
+    ]
+  `);
+});
+
+test('throw error on broken file', () => {
+  const view = makeViewFromBuffer(
+    Buffer.from([0x27, 0x00, 0x00, 0x00, 0x7f, 0x03, 0x6b, 0x65, 0x79, 0x06, 0x07, 0x62, 0x61, 0x64, 0xff, 0xff]),
+  );
+
+  expect(() => Object.fromEntries(MMKVParser.toStringMap(view).entries())).toThrow(/offset mismatch/i);
 });
diff --git a/src/util/__tests__/__fixture__/kuwo.mmkv b/src/util/__tests__/__fixture__/kuwo.mmkv
new file mode 100644
index 0000000..e8261c6
Binary files /dev/null and b/src/util/__tests__/__fixture__/kuwo.mmkv differ
diff --git a/src/util/__tests__/__fixture__/test.mmkv b/src/util/__tests__/__fixture__/qm.mmkv
similarity index 100%
rename from src/util/__tests__/__fixture__/test.mmkv
rename to src/util/__tests__/__fixture__/qm.mmkv
diff --git a/src/util/__tests__/__fixture__/qm_optional.mmkv b/src/util/__tests__/__fixture__/qm_optional.mmkv
new file mode 100644
index 0000000..5e127d9
Binary files /dev/null and b/src/util/__tests__/__fixture__/qm_optional.mmkv differ