diff --git a/src/decrypt/qmc.test.ts b/src/decrypt/qmc.test.ts
index 9fee8ee..73156bd 100644
--- a/src/decrypt/qmc.test.ts
+++ b/src/decrypt/qmc.test.ts
@@ -18,7 +18,7 @@ function loadTestDataDecoder(name: string): {
 }
 
 test('qmc: real file', async () => {
-  const cases = ['mflac0_rc4', 'mflac_map', 'mgg_map', 'qmc0_static'];
+  const cases = ['mflac0_rc4', 'mflac_rc4', 'mflac_map', 'mgg_map', 'qmc0_static'];
   for (const name of cases) {
     const { clearText, cipherText } = loadTestDataDecoder(name);
     const c = new QmcDecoder(cipherText);
diff --git a/src/decrypt/qmc_cipher.test.ts b/src/decrypt/qmc_cipher.test.ts
index 4c574f7..0f1e0b7 100644
--- a/src/decrypt/qmc_cipher.test.ts
+++ b/src/decrypt/qmc_cipher.test.ts
@@ -69,7 +69,7 @@ test('map cipher: real file', async () => {
 });
 
 test('rc4 cipher: real file', async () => {
-  const cases = ['mflac0_rc4'];
+  const cases = ['mflac0_rc4', 'mflac_rc4'];
   for (const name of cases) {
     const { key, clearText, cipherText } = loadTestDataCipher(name);
     const c = new QmcRC4Cipher(key);
@@ -81,7 +81,7 @@ test('rc4 cipher: real file', async () => {
 });
 
 test('rc4 cipher: first segment', async () => {
-  const cases = ['mflac0_rc4'];
+  const cases = ['mflac0_rc4', 'mflac_rc4'];
   for (const name of cases) {
     const { key, clearText, cipherText } = loadTestDataCipher(name);
     const c = new QmcRC4Cipher(key);
@@ -93,7 +93,7 @@ test('rc4 cipher: first segment', async () => {
 });
 
 test('rc4 cipher: align block (128~5120)', async () => {
-  const cases = ['mflac0_rc4'];
+  const cases = ['mflac0_rc4', 'mflac_rc4'];
   for (const name of cases) {
     const { key, clearText, cipherText } = loadTestDataCipher(name);
     const c = new QmcRC4Cipher(key);
@@ -105,7 +105,7 @@ test('rc4 cipher: align block (128~5120)', async () => {
 });
 
 test('rc4 cipher: simple block (5120~10240)', async () => {
-  const cases = ['mflac0_rc4'];
+  const cases = ['mflac0_rc4', 'mflac_rc4'];
   for (const name of cases) {
     const { key, clearText, cipherText } = loadTestDataCipher(name);
     const c = new QmcRC4Cipher(key);
diff --git a/src/decrypt/qmc_cipher.ts b/src/decrypt/qmc_cipher.ts
index 14c0a50..d0d3683 100644
--- a/src/decrypt/qmc_cipher.ts
+++ b/src/decrypt/qmc_cipher.ts
@@ -119,7 +119,7 @@ export class QmcRC4Cipher implements QmcStreamCipher {
       // ignore if key char is '\x00'
       if (!value) continue;
 
-      const next_hash = (this.hash * value) & 0xffffffff;
+      const next_hash = (this.hash * value) >>> 0;
       if (next_hash == 0 || next_hash <= this.hash) break;
 
       this.hash = next_hash;
@@ -174,7 +174,8 @@ export class QmcRC4Cipher implements QmcStreamCipher {
 
     // Calculate the number of bytes to skip.
     // The initial "key" derived from segment id, plus the current offset.
-    const skipLen = (offset % QmcRC4Cipher.SEGMENT_SIZE) + this.getSegmentKey(offset / QmcRC4Cipher.SEGMENT_SIZE);
+    const skipLen =
+      (offset % QmcRC4Cipher.SEGMENT_SIZE) + this.getSegmentKey(Math.floor(offset / QmcRC4Cipher.SEGMENT_SIZE));
 
     // decrypt the block
     let j = 0;
@@ -192,7 +193,7 @@ export class QmcRC4Cipher implements QmcStreamCipher {
 
   private getSegmentKey(id: number): number {
     const seed = this.key[id % this.N];
-    const idx = ((this.hash / ((id + 1) * seed)) * 100.0) | 0;
+    const idx = Math.floor((this.hash / ((id + 1) * seed)) * 100.0);
     return idx % this.N;
   }
 }
diff --git a/src/decrypt/qmc_key.test.ts b/src/decrypt/qmc_key.test.ts
index da392cc..2ec1e96 100644
--- a/src/decrypt/qmc_key.test.ts
+++ b/src/decrypt/qmc_key.test.ts
@@ -16,7 +16,7 @@ function loadTestDataKeyDecrypt(name: string): {
 }
 
 test('key dec: real file', async () => {
-  const cases = ['mflac_map', 'mgg_map', 'mflac0_rc4'];
+  const cases = ['mflac_map', 'mgg_map', 'mflac0_rc4', 'mflac_rc4'];
   for (const name of cases) {
     const { clearText, cipherText } = loadTestDataKeyDecrypt(name);
     const buf = QmcDeriveKey(cipherText);
diff --git a/testdata/mflac_rc4_key.bin b/testdata/mflac_rc4_key.bin
new file mode 100644
index 0000000..8f1104c
--- /dev/null
+++ b/testdata/mflac_rc4_key.bin
@@ -0,0 +1 @@
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
\ No newline at end of file
diff --git a/testdata/mflac_rc4_key_raw.bin b/testdata/mflac_rc4_key_raw.bin
new file mode 100644
index 0000000..1633371
--- /dev/null
+++ b/testdata/mflac_rc4_key_raw.bin
@@ -0,0 +1 @@
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
\ No newline at end of file
diff --git a/testdata/mflac_rc4_raw.bin b/testdata/mflac_rc4_raw.bin
new file mode 100644
index 0000000..6f02875
Binary files /dev/null and b/testdata/mflac_rc4_raw.bin differ
diff --git a/testdata/mflac_rc4_suffix.bin b/testdata/mflac_rc4_suffix.bin
new file mode 100644
index 0000000..3762b4c
Binary files /dev/null and b/testdata/mflac_rc4_suffix.bin differ
diff --git a/testdata/mflac_rc4_target.bin b/testdata/mflac_rc4_target.bin
new file mode 100644
index 0000000..f99e219
Binary files /dev/null and b/testdata/mflac_rc4_target.bin differ