diff --git a/fs/config.go b/fs/config.go
index faf7e02cb..1b5987fd3 100644
--- a/fs/config.go
+++ b/fs/config.go
@@ -6,6 +6,7 @@ import (
 	"bufio"
 	"fmt"
 	"log"
+	"math"
 	"os"
 	"os/user"
 	"path"
@@ -46,21 +47,30 @@ var (
 )
 
 func init() {
-	pflag.VarP(&bwLimit, "bwlimit", "", "Bandwidth limit in kBytes/s, or use suffix K|M|G")
+	pflag.VarP(&bwLimit, "bwlimit", "", "Bandwidth limit in kBytes/s, or use suffix k|M|G")
 }
 
 // Turn SizeSuffix into a string
-func (x *SizeSuffix) String() string {
+func (x SizeSuffix) String() string {
+	scaled := float64(0)
+	suffix := ""
 	switch {
-	case *x == 0:
+	case x == 0:
 		return "0"
-	case *x < 1024*1024:
-		return fmt.Sprintf("%.3fk", float64(*x)/1024)
-	case *x < 1024*1024*1024:
-		return fmt.Sprintf("%.3fM", float64(*x)/1024/1024)
+	case x < 1024*1024:
+		scaled = float64(x) / 1024
+		suffix = "k"
+	case x < 1024*1024*1024:
+		scaled = float64(x) / 1024 / 1024
+		suffix = "M"
 	default:
-		return fmt.Sprintf("%.3fG", float64(*x)/1024/1024/1024)
+		scaled = float64(x) / 1024 / 1024 / 1024
+		suffix = "G"
 	}
+	if math.Floor(scaled) == scaled {
+		return fmt.Sprintf("%.0f%s", scaled, suffix)
+	}
+	return fmt.Sprintf("%.3f%s", scaled, suffix)
 }
 
 // Set a SizeSuffix
@@ -89,6 +99,9 @@ func (x *SizeSuffix) Set(s string) error {
 	if err != nil {
 		return err
 	}
+	if value < 0 {
+		return fmt.Errorf("Size can't be negative %q", s)
+	}
 	value *= multiplier
 	*x = SizeSuffix(value)
 	return nil
diff --git a/fs/config_test.go b/fs/config_test.go
index f0989ece9..00bb6d723 100644
--- a/fs/config_test.go
+++ b/fs/config_test.go
@@ -9,10 +9,11 @@ func TestSizeSuffixString(t *testing.T) {
 	}{
 		{0, "0"},
 		{102, "0.100k"},
-		{1024, "1.000k"},
-		{1024 * 1024, "1.000M"},
-		{1024 * 1024 * 1024, "1.000G"},
-		{10 * 1024 * 1024 * 1024, "10.000G"},
+		{1024, "1k"},
+		{1024 * 1024, "1M"},
+		{1024 * 1024 * 1024, "1G"},
+		{10 * 1024 * 1024 * 1024, "10G"},
+		{10.1 * 1024 * 1024 * 1024, "10.100G"},
 	} {
 		ss := SizeSuffix(test.in)
 		got := ss.String()
@@ -41,6 +42,7 @@ func TestSizeSuffixSet(t *testing.T) {
 		{"1p", 0, true},
 		{"1.p", 0, true},
 		{"1p", 0, true},
+		{"-1K", 0, true},
 	} {
 		ss := SizeSuffix(0)
 		err := ss.Set(test.in)