diff --git a/example/hang/main.go b/example/hang/main.go
index f281397..8dffb97 100644
--- a/example/hang/main.go
+++ b/example/hang/main.go
@@ -19,7 +19,7 @@
 		return fmt.Sprintf("%-7s", str)
 	}
 
-	p := mpb.New()
+	p := mpb.New(nil)
 	bar := p.AddBar(totalItem).PrependFunc(decor).AppendETA(-6)
 
 	blockSize := rand.Intn(maxBlockSize) + 1
diff --git a/example/io/multiple/main.go b/example/io/multiple/main.go
index 1a07461..8f7f073 100644
--- a/example/io/multiple/main.go
+++ b/example/io/multiple/main.go
@@ -19,7 +19,7 @@
 	url2 := "https://homebrew.bintray.com/bottles/libtiff-4.0.7.sierra.bottle.tar.gz"
 
 	var wg sync.WaitGroup
-	p := mpb.New().SetWidth(60)
+	p := mpb.New(nil).SetWidth(60)
 
 	for i, url := range [...]string{url1, url2} {
 		wg.Add(1)
@@ -59,7 +59,7 @@
 	}
 
 	// create bar with appropriate decorators
-	bar := p.AddBar(int(size)).
+	bar := p.AddBar(size).
 		PrependName(name, len(name)).
 		PrependCounters(mpb.UnitBytes, 20).
 		AppendETA(-6)
diff --git a/example/io/single/main.go b/example/io/single/main.go
index 8508cae..fca49ec 100644
--- a/example/io/single/main.go
+++ b/example/io/single/main.go
@@ -35,9 +35,9 @@
 	}
 	defer dest.Close()
 
-	p := mpb.New().SetWidth(64)
+	p := mpb.New(nil).SetWidth(64)
 
-	bar := p.AddBar(int(size)).PrependCounters(mpb.UnitBytes, 20).AppendETA(-6)
+	bar := p.AddBar(size).PrependCounters(mpb.UnitBytes, 20).AppendETA(-6)
 
 	// create proxy reader
 	reader := bar.ProxyReader(resp.Body)
diff --git a/example/prependETA/main.go b/example/prependETA/main.go
index a6a2625..f8dd01a 100644
--- a/example/prependETA/main.go
+++ b/example/prependETA/main.go
@@ -16,8 +16,8 @@
 func main() {
 
 	var wg sync.WaitGroup
-	p := mpb.New().SetWidth(64)
-	// p := mpb.New().RefreshRate(80 * time.Millisecond).SetWidth(64)
+	p := mpb.New(nil).SetWidth(64)
+	// p := mpb.New(nil).RefreshRate(80 * time.Millisecond).SetWidth(64)
 
 	name1 := "Bar#1: "
 	bar1 := p.AddBar(50).
diff --git a/example/prependElapsed/main.go b/example/prependElapsed/main.go
index 291cec7..bc7ee9a 100644
--- a/example/prependElapsed/main.go
+++ b/example/prependElapsed/main.go
@@ -16,8 +16,8 @@
 func main() {
 
 	var wg sync.WaitGroup
-	p := mpb.New().SetWidth(64)
-	// p := mpb.New().RefreshRate(80 * time.Millisecond).SetWidth(64)
+	p := mpb.New(nil).SetWidth(64)
+	// p := mpb.New(nil).RefreshRate(80 * time.Millisecond).SetWidth(64)
 
 	name1 := "Bar#1: "
 	bar1 := p.AddBar(50).
diff --git a/example/remove/main.go b/example/remove/main.go
index a9c372f..d47b750 100644
--- a/example/remove/main.go
+++ b/example/remove/main.go
@@ -16,8 +16,8 @@
 func main() {
 
 	var wg sync.WaitGroup
-	p := mpb.New().SetWidth(64)
-	// p := mpb.New().RefreshRate(100 * time.Millisecond).SetWidth(64)
+	p := mpb.New(nil).SetWidth(64)
+	// p := mpb.New(nil).RefreshRate(100 * time.Millisecond).SetWidth(64)
 
 	name1 := "Bar#1: "
 	bar1 := p.AddBar(50).
diff --git a/example/simple/main.go b/example/simple/main.go
index ca513fb..0c01e84 100644
--- a/example/simple/main.go
+++ b/example/simple/main.go
@@ -11,7 +11,7 @@
 
 func main() {
 	var wg sync.WaitGroup
-	p := mpb.New() // Star mpb's rendering goroutine
+	p := mpb.New(nil) // Star mpb's rendering goroutine
 	for i := 0; i < 3; i++ {
 		wg.Add(1) // add wg delta
 		name := fmt.Sprintf("Bar#%d:", i)
diff --git a/example/singleBar/main.go b/example/singleBar/main.go
index 7e230a2..d23a8f3 100644
--- a/example/singleBar/main.go
+++ b/example/singleBar/main.go
@@ -11,7 +11,7 @@
 func main() {
 
 	name := "Single bar:"
-	p := mpb.New()
+	p := mpb.New(nil)
 	bar := p.AddBar(100).PrependName(name, 0).AppendPercentage()
 
 	for i := 0; i < 100; i++ {
diff --git a/example/sort/main.go b/example/sort/main.go
index 6e53521..213e41f 100644
--- a/example/sort/main.go
+++ b/example/sort/main.go
@@ -16,7 +16,7 @@
 func main() {
 
 	var wg sync.WaitGroup
-	p := mpb.New().SetWidth(60).WithSort(mpb.SortTop)
+	p := mpb.New(nil).SetWidth(60).WithSort(mpb.SortTop)
 
 	name1 := "Bar#1: "
 	bar1 := p.AddBar(100).
diff --git a/format.go b/format.go
index 8da03fa..de77992 100644
--- a/format.go
+++ b/format.go
@@ -20,12 +20,12 @@
 	UnitBytes
 )
 
-func Format(i int) *formatter {
+func Format(i int64) *formatter {
 	return &formatter{n: i}
 }
 
 type formatter struct {
-	n     int
+	n     int64
 	unit  Units
 	width int
 }
@@ -49,7 +49,7 @@
 	}
 }
 
-func formatBytes(i int) (result string) {
+func formatBytes(i int64) (result string) {
 	switch {
 	case i > bytesInTiB:
 		result = fmt.Sprintf("%.1fTiB", float64(i)/bytesInTiB)