diff --git a/src/ssn/decryption/decryptChunk.ts b/src/ssn/decryption/decryptChunk.ts
index b733a85..fcab808 100644
--- a/src/ssn/decryption/decryptChunk.ts
+++ b/src/ssn/decryption/decryptChunk.ts
@@ -12,7 +12,7 @@ export default function getDecryptor(decryptionKeys: [number, number, number]) {
       let curChar = encryptedChunk.readUInt8(i);
 
       //decrypt byte
-      const keyPart = (key2 | 2) & 0xFFFF;
+      const keyPart = ((key2 | 2) >>> 0) & 0xFFFF;
       const decryptedByte = int32Mul(keyPart, keyPart ^ 1) >>> 8;
       curChar = (curChar ^ (decryptedByte & 0xFF)) & 0xFF;
 
diff --git a/src/ssn/decryption/lib/updateKeys.ts b/src/ssn/decryption/lib/updateKeys.ts
index 986bd0d..966c073 100644
--- a/src/ssn/decryption/lib/updateKeys.ts
+++ b/src/ssn/decryption/lib/updateKeys.ts
@@ -3,7 +3,7 @@ import int32Mul from './int32Mul';
 
 export default function updateKeys([key0, key1, key2]: [number, number, number], curChar: number): [number, number, number] {
   key0 = getCrc(key0, curChar);
-  key1 = ((int32Mul(((key1 + (key0 & 0xFF)) >>> 0), 134775813) >>> 0) + 1) >>> 0;
+  key1 = ((int32Mul((((key1 >>> 0) + ((key0 >>> 0) & 0xFF)) >>> 0), 134775813) >>> 0) + 1) >>> 0;
   key2 = getCrc(key2, key1 >>> 24);
 
   return [key0, key1, key2];