diff --git a/totp.go b/totp.go
index b0b0771..7695468 100644
--- a/totp.go
+++ b/totp.go
@@ -33,9 +33,8 @@ func (t *TOTP) Now() string {
 
 // Generate the current time OTP and expiration time
 func (t *TOTP) NowWithExpiration() (string, int64) {
-	interval64 := int64(t.interval)
-	timeCodeInt64 := time.Now().Unix() / interval64
-	expirationTime := (timeCodeInt64 + 1) * interval64
+	timeCodeInt64 := t.timecode(currentTimestamp())
+	expirationTime := (timeCodeInt64 + 1) * int64(t.interval)
 	return t.generateOTP(timeCodeInt64), expirationTime
 }