diff --git a/fs/config.go b/fs/config.go
index 98e89cea0..258b57931 100644
--- a/fs/config.go
+++ b/fs/config.go
@@ -102,6 +102,8 @@ func (x SizeSuffix) String() string {
 	scaled := float64(0)
 	suffix := ""
 	switch {
+	case x < 0:
+		return "off"
 	case x == 0:
 		return "0"
 	case x < 1024:
@@ -128,6 +130,10 @@ func (x *SizeSuffix) Set(s string) error {
 	if len(s) == 0 {
 		return fmt.Errorf("Empty string")
 	}
+	if strings.ToLower(s) == "off" {
+		*x = -1
+		return nil
+	}
 	suffix := s[len(s)-1]
 	suffixLen := 1
 	var multiplier float64
diff --git a/fs/config_test.go b/fs/config_test.go
index e77b272de..a1da2b17d 100644
--- a/fs/config_test.go
+++ b/fs/config_test.go
@@ -18,6 +18,8 @@ func TestSizeSuffixString(t *testing.T) {
 		{1024 * 1024 * 1024, "1G"},
 		{10 * 1024 * 1024 * 1024, "10G"},
 		{10.1 * 1024 * 1024 * 1024, "10.100G"},
+		{-1, "off"},
+		{-100, "off"},
 	} {
 		ss := SizeSuffix(test.in)
 		got := ss.String()
@@ -44,6 +46,8 @@ func TestSizeSuffixSet(t *testing.T) {
 		{"1M", 1024 * 1024, false},
 		{"1.g", 1024 * 1024 * 1024, false},
 		{"10G", 10 * 1024 * 1024 * 1024, false},
+		{"off", -1, false},
+		{"OFF", -1, false},
 		{"", 0, true},
 		{"1p", 0, true},
 		{"1.p", 0, true},