diff --git a/src/ssn/decryption/decryptChunk.ts b/src/ssn/decryption/decryptChunk.ts
index 7b7fad0..b733a85 100644
--- a/src/ssn/decryption/decryptChunk.ts
+++ b/src/ssn/decryption/decryptChunk.ts
@@ -1,3 +1,4 @@
+import int32Mul from './lib/int32Mul';
 import updateKeys from './lib/updateKeys';
 
 export default function getDecryptor(decryptionKeys: [number, number, number]) {
@@ -12,7 +13,7 @@ export default function getDecryptor(decryptionKeys: [number, number, number]) {
 
       //decrypt byte
       const keyPart = (key2 | 2) & 0xFFFF;
-      const decryptedByte = (keyPart * (keyPart ^ 1)) >>> 8;
+      const decryptedByte = int32Mul(keyPart, keyPart ^ 1) >>> 8;
       curChar = (curChar ^ (decryptedByte & 0xFF)) & 0xFF;
 
       //update keys