diff --git a/rate.go b/rate.go
index 5b22409..f3f917c 100644
--- a/rate.go
+++ b/rate.go
@@ -1,10 +1,11 @@
 package limiter
 
 import (
-	"fmt"
 	"strconv"
 	"strings"
 	"time"
+
+	"github.com/pkg/errors"
 )
 
 // Rate is the rate.
@@ -20,7 +21,7 @@ func NewRateFromFormatted(formatted string) (Rate, error) {
 
 	values := strings.Split(formatted, "-")
 	if len(values) != 2 {
-		return rate, fmt.Errorf("Incorrect format '%s'", formatted)
+		return rate, errors.Errorf("incorrect format '%s'", formatted)
 	}
 
 	periods := map[string]time.Duration{
@@ -32,26 +33,21 @@ func NewRateFromFormatted(formatted string) (Rate, error) {
 	limit, period := values[0], strings.ToUpper(values[1])
 
 	duration, ok := periods[period]
-
 	if !ok {
-		return rate, fmt.Errorf("Incorrect period '%s'", period)
+		return rate, errors.Errorf("incorrect period '%s'", period)
 	}
 
-	var (
-		p time.Duration
-		l int
-	)
-
-	p = 1 * duration
-
-	l, err := strconv.Atoi(limit)
+	p := 1 * duration
+	l, err := strconv.ParseInt(limit, 10, 64)
 	if err != nil {
-		return rate, fmt.Errorf("Incorrect limit '%s'", limit)
+		return rate, errors.Errorf("incorrect limit '%s'", limit)
 	}
 
-	return Rate{
+	rate = Rate{
 		Formatted: formatted,
 		Period:    p,
-		Limit:     int64(l),
-	}, nil
+		Limit:     l,
+	}
+
+	return rate, nil
 }
diff --git a/rate_test.go b/rate_test.go
index dc64aac..3078570 100644
--- a/rate_test.go
+++ b/rate_test.go
@@ -5,11 +5,13 @@ import (
 	"testing"
 	"time"
 
-	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 // TestRate tests Rate methods.
 func TestRate(t *testing.T) {
+	is := require.New(t)
+
 	expected := map[string]Rate{
 		"10-S": {
 			Formatted: "10-S",
@@ -30,8 +32,8 @@ func TestRate(t *testing.T) {
 
 	for k, v := range expected {
 		r, err := NewRateFromFormatted(k)
-		assert.Nil(t, err)
-		assert.True(t, reflect.DeepEqual(v, r))
+		is.NoError(err)
+		is.True(reflect.DeepEqual(v, r))
 	}
 
 	wrongs := []string{
@@ -44,7 +46,7 @@ func TestRate(t *testing.T) {
 
 	for _, w := range wrongs {
 		_, err := NewRateFromFormatted(w)
-		assert.NotNil(t, err)
+		is.Error(err)
 	}
 
 }