diff --git a/partner-otomax.js b/partner-otomax.js
index 6f76b97..1e53ec6 100644
--- a/partner-otomax.js
+++ b/partner-otomax.js
@@ -125,10 +125,11 @@ function parseMessage(task, message) {
 
 function generateSign(userid, remoteProduct, destination, requestId, pin, password) {
     let plain = ["OtomaX", userid, remoteProduct, destination, requestId, pin, password].join("|");
-    let sha1 = crypto.createHash('sha1').update(plain).digest().toString('hex');
-    let buffer = new Buffer(sha1);
+    //let sha1 = crypto.createHash('sha1').update(plain).digest().toString('hex');
+    //let buffer = new Buffer(sha1);
+    let buffer = crypto.createHash('sha1').update(plain).digest();
 
-    return buffer.toString('base64');
+    return buffer.toString('base64').replace(/\//g, '_');
 }
 
 function createRequestOptions(task) {
diff --git a/test.js b/test.js
index 9b352ed..4e13451 100644
--- a/test.js
+++ b/test.js
@@ -4,7 +4,7 @@ var partner = require('./partner-otomax');
 describe ('#partner', function() {
     describe('generateSign', function() {
         it('should return correct sign based on example from otomax doc', function() {
-            partner.generateSign('YUSUF', 'XX10', '08123456789', '2140669', '1144', 'abcd').should.equal('YmU1YWNkZjU4YmFlZTMxMWMwNGZjZmRiNWM4NTA3MmIwZDhkOGM3YQ==');
+            partner.generateSign('YUSUF', 'XX10', '08123456789', '2140669', '1144', 'abcd').should.equal('vlrN9Yuu4xHAT8_bXIUHKw2NjHo=');
         })
     });
 });