diff --git a/gofsutil.go b/gofsutil.go
index ed58e92..10045cd 100644
--- a/gofsutil.go
+++ b/gofsutil.go
@@ -86,7 +86,7 @@ var (
 	ErrNotImplemented = errors.New("not implemented")
 
 	// fs is the default FS instance.
-	fs FSinterface = &FS{ScanEntry: defaultEntryScanFunc, SysBlockDir: "/sys/block"}
+	fs FSinterface = &FS{ScanEntry: defaultEntryScanFunc}
 )
 
 // ContextKey is a variable containing context-keys
@@ -102,11 +102,6 @@ func UseMockFS() {
 	fs = &mockfs{ScanEntry: defaultEntryScanFunc}
 }
 
-// UseMockSysBlockDir creates a file system for testing.
-func UseMockSysBlockDir(mockSysBlockDir string) {
-	fs = &FS{ScanEntry: defaultEntryScanFunc, SysBlockDir: mockSysBlockDir}
-}
-
 // GetDiskFormat uses 'lsblk' to see if the given disk is unformatted.
 func GetDiskFormat(ctx context.Context, disk string) (string, error) {
 	return fs.GetDiskFormat(ctx, disk)
diff --git a/gofsutil_fs.go b/gofsutil_fs.go
index 88a4667..89ed783 100644
--- a/gofsutil_fs.go
+++ b/gofsutil_fs.go
@@ -19,12 +19,13 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+// SysBlockDir is used to set the directory of block devices.
+var SysBlockDir string = "/sys/block"
+
 // FS provides many filesystem-specific functions, such as mount, format, etc.
 type FS struct {
 	// ScanEntry is the function used to process mount table entries.
 	ScanEntry EntryScanFunc
-	// SysBlockDir is used to set the directory of block devices.
-	SysBlockDir string
 }
 
 // GetDiskFormat uses 'lsblk' to see if the given disk is unformatted.
diff --git a/gofsutil_mount_test.go b/gofsutil_mount_test.go
index f783b88..a2f1939 100644
--- a/gofsutil_mount_test.go
+++ b/gofsutil_mount_test.go
@@ -89,7 +89,7 @@ func TestGetMounts(t *testing.T) {
 
 func TestGetSysBlockDevicesForVolumeWWN(t *testing.T) {
 	tempDir := t.TempDir()
-	gofsutil.UseMockSysBlockDir(tempDir)
+	gofsutil.SysBlockDir = tempDir
 
 	tests := []struct {
 		name           string
@@ -153,7 +153,7 @@ func TestGetSysBlockDevicesForVolumeWWN(t *testing.T) {
 
 func TestGetNVMeController(t *testing.T) {
 	tempDir := t.TempDir()
-	gofsutil.UseMockSysBlockDir(tempDir)
+	gofsutil.SysBlockDir = tempDir
 
 	tests := map[string]struct {
 		device      string
diff --git a/gofsutil_mount_unix.go b/gofsutil_mount_unix.go
index 4b4f116..bb495b0 100644
--- a/gofsutil_mount_unix.go
+++ b/gofsutil_mount_unix.go
@@ -650,9 +650,9 @@ func (fs *FS) issueLIPToAllFCHosts(_ context.Context) error {
 func (fs *FS) getSysBlockDevicesForVolumeWWN(_ context.Context, volumeWWN string) ([]string, error) {
 	start := time.Now()
 	result := make([]string, 0)
-	sysBlocks, err := os.ReadDir(fs.SysBlockDir)
+	sysBlocks, err := os.ReadDir(SysBlockDir)
 	if err != nil {
-		return result, fmt.Errorf("Error reading %s: %s", fs.SysBlockDir, err)
+		return result, fmt.Errorf("Error reading %s: %s", SysBlockDir, err)
 	}
 
 	for _, sysBlock := range sysBlocks {
@@ -665,9 +665,9 @@ func (fs *FS) getSysBlockDevicesForVolumeWWN(_ context.Context, volumeWWN string
 		// Set the WWID path based on the device type
 		var wwidPath string
 		if strings.HasPrefix(name, "nvme") {
-			wwidPath = fs.SysBlockDir + "/" + name + "/wwid" // For NVMe devices
+			wwidPath = SysBlockDir + "/" + name + "/wwid" // For NVMe devices
 		} else {
-			wwidPath = fs.SysBlockDir + "/" + name + "/device/wwid" // For SCSI devices
+			wwidPath = SysBlockDir + "/" + name + "/device/wwid" // For SCSI devices
 		}
 
 		bytes, err := os.ReadFile(filepath.Clean(wwidPath))
@@ -746,7 +746,7 @@ func wwnMatches(nguid, wwn string) bool {
 
 // GetNVMeController retrieves the NVMe controller for a given NVMe device.
 func (fs *FS) getNVMeController(device string) (string, error) {
-	devicePath := filepath.Join(fs.SysBlockDir, device)
+	devicePath := filepath.Join(SysBlockDir, device)
 
 	// Check if the device path exists
 	if _, err := os.Stat(devicePath); os.IsNotExist(err) {
diff --git a/gofsutil_unix_test.go b/gofsutil_unix_test.go
index 938dc96..d4f95f1 100644
--- a/gofsutil_unix_test.go
+++ b/gofsutil_unix_test.go
@@ -132,6 +132,9 @@ func TestMountArgs(t *testing.T) {
 }
 
 func TestWWNToDevicePath(t *testing.T) {
+	tempDir := t.TempDir()
+	SysBlockDir = tempDir
+
 	tests := []struct {
 		src    string
 		tgt    string
@@ -251,7 +254,7 @@ func TestValidateMountArgs(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.testname, func(t *testing.T) {
-			fs := FS{SysBlockDir: "string"}
+			fs := FS{}
 			err := fs.validateMountArgs(tt.source, tt.target, tt.fstype, tt.opts...)
 			assert.Equal(t, tt.expect, err)
 		})
@@ -291,7 +294,7 @@ func TestDoMount(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.testname, func(t *testing.T) {
-			fs := FS{SysBlockDir: "string"}
+			fs := FS{}
 			err := fs.doMount(tt.ctx, tt.mntCmnd, tt.source, tt.target, tt.fstype, tt.opts...)
 			assert.Equal(t, true, strings.Contains(err.Error(), tt.expect))
 		})
@@ -319,7 +322,7 @@ func TestUnMount(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.testname, func(t *testing.T) {
-			fs := FS{SysBlockDir: "string"}
+			fs := FS{}
 			err := fs.unmount(tt.ctx, tt.target)
 			assert.Equal(t, true, strings.Contains(err.Error(), tt.expect))
 		})
@@ -398,7 +401,7 @@ func TestMultipathCommand(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.testname, func(t *testing.T) {
-			fs := FS{SysBlockDir: "string"}
+			fs := FS{}
 			_, err := fs.multipathCommand(tt.ctx, tt.timeoutSeconds, tt.chroot, tt.arguments...)
 			assert.Equal(t, tt.expectErr, err)
 		})
@@ -421,7 +424,7 @@ func TestIsBind(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.testname, func(t *testing.T) {
-			fs := FS{SysBlockDir: "string"}
+			fs := FS{}
 			_, err := fs.isBind(tt.ctx, tt.opts...)
 			assert.Equal(t, tt.expect, err)
 		})