diff --git a/graphdriver/devmapper/deviceset.go b/graphdriver/devmapper/deviceset.go
index 66e44e3da..ce66211ca 100644
--- a/graphdriver/devmapper/deviceset.go
+++ b/graphdriver/devmapper/deviceset.go
@@ -12,7 +12,6 @@ import (
 	"path/filepath"
 	"strconv"
 	"sync"
-	"syscall"
 	"time"
 )
 
@@ -344,7 +343,7 @@ func setCloseOnExec(name string) {
 			if link == name {
 				fd, err := strconv.Atoi(i.Name())
 				if err == nil {
-					SyscallCloseOnExec(fd)
+					sysCloseOnExec(fd)
 				}
 			}
 		}
@@ -468,7 +467,7 @@ func (devices *DeviceSet) initDevmapper(doInit bool) error {
 	if err != nil {
 		return fmt.Errorf("Error looking up dir %s: %s", devices.root, err)
 	}
-	sysSt := st.Sys().(*syscall.Stat_t)
+	sysSt := toSysStatT(st.Sys())
 	// "reg-" stands for "regular file".
 	// In the future we might use "dev-" for "device file", etc.
 	// docker-maj,min[-inode] stands for:
@@ -708,15 +707,16 @@ func (devices *DeviceSet) byHash(hash string) (devname string, err error) {
 }
 
 func (devices *DeviceSet) Shutdown() error {
-	utils.Debugf("[deviceset %s] shutdown()", devices.devicePrefix)
-	defer utils.Debugf("[deviceset %s] shutdown END", devices.devicePrefix)
 	devices.Lock()
-	utils.Debugf("[devmapper] Shutting down DeviceSet: %s", devices.root)
 	defer devices.Unlock()
 
+	utils.Debugf("[deviceset %s] shutdown()", devices.devicePrefix)
+	utils.Debugf("[devmapper] Shutting down DeviceSet: %s", devices.root)
+	defer utils.Debugf("[deviceset %s] shutdown END", devices.devicePrefix)
+
 	for path, count := range devices.activeMounts {
 		for i := count; i > 0; i-- {
-			if err := SyscallUnmount(path, 0); err != nil {
+			if err := sysUnmount(path, 0); err != nil {
 				utils.Debugf("Shutdown unmounting %s, error: %s\n", path, err)
 			}
 		}
@@ -752,15 +752,15 @@ func (devices *DeviceSet) MountDevice(hash, path string, readOnly bool) error {
 
 	info := devices.Devices[hash]
 
-	var flags uintptr = syscall.MS_MGC_VAL
+	var flags uintptr = sysMsMgcVal
 
 	if readOnly {
-		flags = flags | syscall.MS_RDONLY
+		flags = flags | sysMsRdOnly
 	}
 
-	err := SyscallMount(info.DevName(), path, "ext4", flags, "discard")
-	if err != nil && err == syscall.EINVAL {
-		err = SyscallMount(info.DevName(), path, "ext4", flags, "")
+	err := sysMount(info.DevName(), path, "ext4", flags, "discard")
+	if err != nil && err == sysEInval {
+		err = sysMount(info.DevName(), path, "ext4", flags, "")
 	}
 	if err != nil {
 		return fmt.Errorf("Error mounting '%s' on '%s': %s", info.DevName(), path, err)
@@ -779,7 +779,7 @@ func (devices *DeviceSet) UnmountDevice(hash, path string, deactivate bool) erro
 	defer devices.Unlock()
 
 	utils.Debugf("[devmapper] Unmount(%s)", path)
-	if err := SyscallUnmount(path, 0); err != nil {
+	if err := sysUnmount(path, 0); err != nil {
 		utils.Debugf("\n--->Err: %s\n", err)
 		return err
 	}
diff --git a/graphdriver/devmapper/devmapper.go b/graphdriver/devmapper/devmapper.go
index 56130bd01..cccb168f9 100644
--- a/graphdriver/devmapper/devmapper.go
+++ b/graphdriver/devmapper/devmapper.go
@@ -6,7 +6,6 @@ import (
 	"github.com/dotcloud/docker/utils"
 	"os"
 	"runtime"
-	"syscall"
 )
 
 type DevmapperLogger interface {
@@ -210,13 +209,13 @@ func FindLoopDeviceFor(file *os.File) *os.File {
 	if err != nil {
 		return nil
 	}
-	targetInode := stat.Sys().(*syscall.Stat_t).Ino
-	targetDevice := stat.Sys().(*syscall.Stat_t).Dev
+	targetInode := stat.Sys().(*sysStatT).Ino
+	targetDevice := stat.Sys().(*sysStatT).Dev
 
 	for i := 0; true; i++ {
 		path := fmt.Sprintf("/dev/loop%d", i)
 
-		file, err := OSOpenFile(path, os.O_RDWR, 0)
+		file, err := osOpenFile(path, os.O_RDWR, 0)
 		if err != nil {
 			if os.IsNotExist(err) {
 				return nil
@@ -394,8 +393,8 @@ func getStatus(name string) (uint64, uint64, string, string, error) {
 		return 0, 0, "", "", fmt.Errorf("Non existing device %s", name)
 	}
 
-	_, start, length, target_type, params := task.GetNextTarget(0)
-	return start, length, target_type, params, nil
+	_, start, length, targetType, params := task.GetNextTarget(0)
+	return start, length, targetType, params, nil
 }
 
 func setTransactionId(poolName string, oldId uint64, newId uint64) error {
diff --git a/graphdriver/devmapper/devmapper_test.go b/graphdriver/devmapper/devmapper_test.go
index 8d93ab30b..33167f095 100644
--- a/graphdriver/devmapper/devmapper_test.go
+++ b/graphdriver/devmapper/devmapper_test.go
@@ -1,7 +1,6 @@
 package devmapper
 
 import (
-	"syscall"
 	"testing"
 )
 
@@ -264,7 +263,7 @@ func dmAttachLoopDeviceFail(filename string, fd *int) string {
 	return ""
 }
 
-func sysGetBlockSizeFail(fd uintptr, size *uint64) syscall.Errno {
+func sysGetBlockSizeFail(fd uintptr, size *uint64) sysErrno {
 	return 1
 }
 
diff --git a/graphdriver/devmapper/devmapper_wrapper.go b/graphdriver/devmapper/devmapper_wrapper.go
index e261db435..00b7ecb38 100644
--- a/graphdriver/devmapper/devmapper_wrapper.go
+++ b/graphdriver/devmapper/devmapper_wrapper.go
@@ -140,7 +140,6 @@ static void	log_with_errno_init()
 import "C"
 
 import (
-	"syscall"
 	"unsafe"
 )
 
@@ -239,23 +238,22 @@ func dmTaskAddTargetFct(task *CDmTask,
 		C.uint64_t(start), C.uint64_t(size), Cttype, Cparams))
 }
 
-func dmGetLoopbackBackingFile(fd uintptr) (uint64, uint64, syscall.Errno) {
+func dmGetLoopbackBackingFile(fd uintptr) (uint64, uint64, sysErrno) {
 	var lo64 C.struct_loop_info64
-	_, _, err := SyscallSyscall(syscall.SYS_IOCTL, fd, C.LOOP_GET_STATUS64,
+	_, _, err := sysSyscall(sysSysIoctl, fd, C.LOOP_GET_STATUS64,
 		uintptr(unsafe.Pointer(&lo64)))
-	return uint64(lo64.lo_device), uint64(lo64.lo_inode), err
+	return uint64(lo64.lo_device), uint64(lo64.lo_inode), sysErrno(err)
 }
 
-func dmLoopbackSetCapacity(fd uintptr) syscall.Errno {
-	_, _, err := SyscallSyscall(syscall.SYS_IOCTL, fd, C.LOOP_SET_CAPACITY, 0)
-	return err
+func dmLoopbackSetCapacity(fd uintptr) sysErrno {
+	_, _, err := sysSyscall(sysSysIoctl, fd, C.LOOP_SET_CAPACITY, 0)
+	return sysErrno(err)
 }
 
-func dmGetBlockSizeFct(fd uintptr) (int64, syscall.Errno) {
+func dmGetBlockSizeFct(fd uintptr) (int64, sysErrno) {
 	var size int64
-	_, _, err := SyscallSyscall(syscall.SYS_IOCTL, fd, C.BLKGETSIZE64,
-		uintptr(unsafe.Pointer(&size)))
-	return size, err
+	_, _, err := sysSyscall(sysSysIoctl, fd, C.BLKGETSIZE64, uintptr(unsafe.Pointer(&size)))
+	return size, sysErrno(err)
 }
 
 func dmTaskGetInfoFct(task *CDmTask, info *Info) int {
@@ -275,9 +273,7 @@ func dmTaskGetInfoFct(task *CDmTask, info *Info) int {
 	return int(C.dm_task_get_info((*C.struct_dm_task)(task), &Cinfo))
 }
 
-func dmGetNextTargetFct(task *CDmTask, next uintptr, start, length *uint64,
-	target, params *string) uintptr {
-
+func dmGetNextTargetFct(task *CDmTask, next uintptr, start, length *uint64, target, params *string) uintptr {
 	var (
 		Cstart, Clength      C.uint64_t
 		CtargetType, Cparams *C.char
@@ -288,6 +284,7 @@ func dmGetNextTargetFct(task *CDmTask, next uintptr, start, length *uint64,
 		*target = C.GoString(CtargetType)
 		*params = C.GoString(Cparams)
 	}()
+
 	nextp := C.dm_get_next_target((*C.struct_dm_task)(task),
 		unsafe.Pointer(next), &Cstart, &Clength, &CtargetType, &Cparams)
 	return uintptr(nextp)
@@ -307,10 +304,9 @@ func dmAttachLoopDeviceFct(filename string, fd *int) string {
 	return C.GoString(ret)
 }
 
-func getBlockSizeFct(fd uintptr, size *uint64) syscall.Errno {
-	_, _, err := SyscallSyscall(syscall.SYS_IOCTL, fd, C.BLKGETSIZE64,
-		uintptr(unsafe.Pointer(&size)))
-	return err
+func getBlockSizeFct(fd uintptr, size *uint64) sysErrno {
+	_, _, err := sysSyscall(sysSysIoctl, fd, C.BLKGETSIZE64, uintptr(unsafe.Pointer(&size)))
+	return sysErrno(err)
 }
 
 func dmUdevWaitFct(cookie uint) int {
diff --git a/graphdriver/devmapper/mount.go b/graphdriver/devmapper/mount.go
index e3a303e50..f066c51bb 100644
--- a/graphdriver/devmapper/mount.go
+++ b/graphdriver/devmapper/mount.go
@@ -3,7 +3,6 @@ package devmapper
 import (
 	"os"
 	"path/filepath"
-	"syscall"
 )
 
 // FIXME: this is copy-pasted from the aufs driver.
@@ -21,7 +20,7 @@ func Mounted(mountpoint string) (bool, error) {
 	if err != nil {
 		return false, err
 	}
-	mntpointSt := mntpoint.Sys().(*syscall.Stat_t)
-	parentSt := parent.Sys().(*syscall.Stat_t)
+	mntpointSt := toSysStatT(mntpoint.Sys())
+	parentSt := toSysStatT(parent.Sys())
 	return mntpointSt.Dev != parentSt.Dev, nil
 }
diff --git a/graphdriver/devmapper/sys.go b/graphdriver/devmapper/sys.go
index c2ba1263f..d5fcde490 100644
--- a/graphdriver/devmapper/sys.go
+++ b/graphdriver/devmapper/sys.go
@@ -1,15 +1,31 @@
 package devmapper
 
-
 import (
+	"os"
 	"syscall"
 )
 
+type (
+	sysStatT syscall.Stat_t
+	sysErrno syscall.Errno
+)
 
 var (
-	SyscallMount		= syscall.Mount
-	SyscallUnmount		= syscall.Unmount
-	SyscallCloseOnExec	= syscall.CloseOnExec
-	SyscallSyscall		= syscall.Syscall
-	OSOpenFile		= os.OpenFile
+	// functions
+	sysMount       = syscall.Mount
+	sysUnmount     = syscall.Unmount
+	sysCloseOnExec = syscall.CloseOnExec
+	sysSyscall     = syscall.Syscall
+	osOpenFile     = os.OpenFile
 )
+
+const (
+	sysMsMgcVal = syscall.MS_MGC_VAL
+	sysMsRdOnly = syscall.MS_RDONLY
+	sysEInval   = syscall.EINVAL
+	sysSysIoctl = syscall.SYS_IOCTL
+)
+
+func toSysStatT(i interface{}) *sysStatT {
+	return (*sysStatT)(i.(*syscall.Stat_t))
+}