diff --git a/totp/totp.go b/totp/totp.go
index a2fb7d5..f4e0ff5 100644
--- a/totp/totp.go
+++ b/totp/totp.go
@@ -18,10 +18,11 @@
 package totp
 
 import (
+	"io"
+
 	"github.com/pquerna/otp"
 	"github.com/pquerna/otp/hotp"
 	"github.com/pquerna/otp/internal"
-	"io"
 
 	"crypto/rand"
 	"encoding/base32"
@@ -100,6 +101,10 @@ func ValidateCustom(passcode string, secret string, t time.Time, opts ValidateOp
 		opts.Period = 30
 	}
 
+	if opts.Skew == 0 {
+		opts.Skew = 1
+	}
+
 	counters := []uint64{}
 	counter := int64(math.Floor(float64(t.Unix()) / float64(opts.Period)))