diff --git a/ntlm/ntlmv2.go b/ntlm/ntlmv2.go
index d4820e8..899abe1 100644
--- a/ntlm/ntlmv2.go
+++ b/ntlm/ntlmv2.go
@@ -221,7 +221,7 @@ func authLdap(username, password string) (bool, error) {
 	return true, nil
 }
 
-func (n *V2ServerSession) ProcessAuthenticateMessage(am *AuthenticateMessage, sChallenge string) (err error) {
+func (n *V2ServerSession) ProcessAuthenticateMessage(am *AuthenticateMessage) (err error) {
 	n.authenticateMessage = am
 	n.NegotiateFlags = am.NegotiateFlags
 	n.clientChallenge = am.ClientChallenge()
@@ -246,15 +246,16 @@ func (n *V2ServerSession) ProcessAuthenticateMessage(am *AuthenticateMessage, sC
 		return err
 	}
 
+	hexServerChallenge := hex.EncodeToString(n.challengeMessage.ServerChallenge)
 	hexNTLMClienteChallenge := hex.EncodeToString(am.NtlmV2Response.Response)
 	hexClientChallenge := hex.EncodeToString(n.clientChallenge)
 
-	log.Printf("DEBUG: challenge Server: %s\n", sChallenge)
+	log.Printf("DEBUG: challenge Server: %s\n", hexServerChallenge)
 	log.Printf("DEBUG: ntChallengeResponse: %s\n", hexNTLMClienteChallenge)
 	log.Printf("DEBUG: ClientChallenge: %s\n", hexClientChallenge)
 
 	// Execute ntlm_auth to check user auth
-	cmd := exec.Command("/usr/local/bin/ntlm_auth", "--domain="+n.userDomain, "--username="+n.user, "--challenge="+sChallenge, "--nt-response="+(hexNTLMClienteChallenge+hexClientChallenge))
+	cmd := exec.Command("/usr/local/bin/ntlm_auth", "--domain="+n.userDomain, "--username="+n.user, "--challenge="+hexServerChallenge, "--nt-response="+(hexNTLMClienteChallenge+hexClientChallenge))
 	output, err := cmd.CombinedOutput()
 	if err != nil {
 		fmt.Printf("Failed to execute command: %s\n", err)