diff --git a/cpu/cpu_linux.go b/cpu/cpu_linux.go
index 6a4e672b1..b36797fb4 100644
--- a/cpu/cpu_linux.go
+++ b/cpu/cpu_linux.go
@@ -3,14 +3,13 @@
 package cpu
 
 import (
-	"path/filepath"
-	"fmt"
 	"errors"
+	"fmt"
 	"os/exec"
 	"strconv"
 	"strings"
 
-	common "github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 var cpu_tick = float64(100)
@@ -27,7 +26,7 @@ func init() {
 }
 
 func CPUTimes(percpu bool) ([]CPUTimesStat, error) {
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/stat"
+	filename := common.HostProc("stat")
 	var lines = []string{}
 	if percpu {
 		var startIdx uint = 1
@@ -58,8 +57,7 @@ func CPUTimes(percpu bool) ([]CPUTimesStat, error) {
 }
 
 func sysCpuPath(cpu int32, relPath string) string {
-	root :=  common.GetEnv("HOST_SYS", "/sys")
-	return filepath.Join(root, fmt.Sprintf("devices/system/cpu/cpu%d", cpu), relPath)
+	return common.HostSys(fmt.Sprintf("devices/system/cpu/cpu%d", cpu), relPath)
 }
 
 func finishCPUInfo(c *CPUInfoStat) error {
@@ -75,7 +73,7 @@ func finishCPUInfo(c *CPUInfoStat) error {
 	}
 	if len(c.CoreID) == 0 {
 		lines, err := common.ReadLines(sysCpuPath(c.CPU, "topology/core_id"))
-		if err == nil {	
+		if err == nil {
 			c.CoreID = lines[0]
 		}
 	}
@@ -83,7 +81,7 @@ func finishCPUInfo(c *CPUInfoStat) error {
 }
 
 func CPUInfo() ([]CPUInfoStat, error) {
-	filename := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), "cpuinfo")
+	filename := common.HostProc("cpuinfo")
 	lines, _ := common.ReadLines(filename)
 
 	var ret []CPUInfoStat
@@ -148,7 +146,7 @@ func CPUInfo() ([]CPUInfoStat, error) {
 				return ret, err
 			}
 			c.Cores = int32(t)
-		case "flags","Features":
+		case "flags", "Features":
 			c.Flags = strings.FieldsFunc(value, func(r rune) bool {
 				return r == ',' || r == ' '
 			})
diff --git a/disk/disk_linux.go b/disk/disk_linux.go
index 93f59b098..caa1e17f7 100644
--- a/disk/disk_linux.go
+++ b/disk/disk_linux.go
@@ -9,7 +9,7 @@ import (
 	"strings"
 	"syscall"
 
-	common "github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 const (
@@ -238,7 +238,7 @@ func DiskPartitions(all bool) ([]DiskPartitionStat, error) {
 }
 
 func DiskIOCounters() (map[string]DiskIOCountersStat, error) {
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/diskstats"
+	filename := common.HostProc("diskstats")
 	lines, err := common.ReadLines(filename)
 	if err != nil {
 		return nil, err
diff --git a/docker/docker_linux.go b/docker/docker_linux.go
index fd6df6d8b..bc2fd6ef3 100644
--- a/docker/docker_linux.go
+++ b/docker/docker_linux.go
@@ -4,14 +4,14 @@ package docker
 
 import (
 	"encoding/json"
-        "os"
+	"os"
 	"os/exec"
 	"path"
 	"strconv"
 	"strings"
 
-	common "github.com/shirou/gopsutil/common"
 	cpu "github.com/shirou/gopsutil/cpu"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 // GetDockerIDList returnes a list of DockerID.
@@ -49,9 +49,9 @@ func CgroupCPU(containerid string, base string) (*cpu.CPUTimesStat, error) {
 	}
 	statfile := path.Join(base, containerid, "cpuacct.stat")
 
-        if _, err := os.Stat(statfile); os.IsNotExist(err) {
-            statfile = path.Join("/sys/fs/cgroup/cpuacct/system.slice",  "docker-" + containerid + ".scope", "cpuacct.stat")
-        }
+	if _, err := os.Stat(statfile); os.IsNotExist(err) {
+		statfile = path.Join("/sys/fs/cgroup/cpuacct/system.slice", "docker-"+containerid+".scope", "cpuacct.stat")
+	}
 
 	lines, err := common.ReadLines(statfile)
 	if err != nil {
@@ -91,9 +91,9 @@ func CgroupMem(containerid string, base string) (*CgroupMemStat, error) {
 	}
 	statfile := path.Join(base, containerid, "memory.stat")
 
-        if _, err := os.Stat(statfile); os.IsNotExist(err) {
-            statfile = path.Join("/sys/fs/cgroup/memory/system.slice",  "docker-" + containerid + ".scope", "memory.stat")
-        }
+	if _, err := os.Stat(statfile); os.IsNotExist(err) {
+		statfile = path.Join("/sys/fs/cgroup/memory/system.slice", "docker-"+containerid+".scope", "memory.stat")
+	}
 
 	// empty containerid means all cgroup
 	if len(containerid) == 0 {
diff --git a/host/host_linux.go b/host/host_linux.go
index 9131fa84d..0ac9ea853 100644
--- a/host/host_linux.go
+++ b/host/host_linux.go
@@ -15,7 +15,7 @@ import (
 	"strings"
 	"unsafe"
 
-	common "github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 type LSB struct {
@@ -56,7 +56,7 @@ func HostInfo() (*HostInfoStat, error) {
 
 // BootTime returns the system boot time expressed in seconds since the epoch.
 func BootTime() (uint64, error) {
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/stat"
+	filename := common.HostProc("stat")
 	lines, err := common.ReadLines(filename)
 	if err != nil {
 		return 0, err
@@ -321,7 +321,7 @@ func GetVirtualization() (string, string, error) {
 	var system string
 	var role string
 
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/xen"
+	filename := common.HostProc("xen")
 	if common.PathExists(filename) {
 		system = "xen"
 		role = "guest" // assume guest
@@ -336,7 +336,7 @@ func GetVirtualization() (string, string, error) {
 		}
 	}
 
-	filename = common.GetEnv("HOST_PROC", "/proc") + "/modules"
+	filename = common.HostProc("modules")
 	if common.PathExists(filename) {
 		contents, err := common.ReadLines(filename)
 		if err == nil {
@@ -353,7 +353,7 @@ func GetVirtualization() (string, string, error) {
 		}
 	}
 
-	filename = common.GetEnv("HOST_PROC", "/proc") + "/cpuinfo"
+	filename = common.HostProc("cpuinfo")
 	if common.PathExists(filename) {
 		contents, err := common.ReadLines(filename)
 		if err == nil {
@@ -366,7 +366,7 @@ func GetVirtualization() (string, string, error) {
 		}
 	}
 
-	filename = common.GetEnv("HOST_PROC", "/proc")
+	filename = common.HostProc()
 	if common.PathExists(filename + "/bc/0") {
 		system = "openvz"
 		role = "host"
diff --git a/host/host_linux_386.go b/host/host_linux_386.go
index d8f31c2f6..fb6d7a0f6 100644
--- a/host/host_linux_386.go
+++ b/host/host_linux_386.go
@@ -6,39 +6,39 @@
 package host
 
 const (
-	sizeofPtr	= 0x4
-	sizeofShort	= 0x2
-	sizeofInt	= 0x4
-	sizeofLong	= 0x4
-	sizeofLongLong	= 0x8
+	sizeofPtr      = 0x4
+	sizeofShort    = 0x2
+	sizeofInt      = 0x4
+	sizeofLong     = 0x4
+	sizeofLongLong = 0x8
 )
 
 type (
-	_C_short	int16
-	_C_int		int32
-	_C_long		int32
-	_C_long_long	int64
+	_C_short     int16
+	_C_int       int32
+	_C_long      int32
+	_C_long_long int64
 )
 
 type utmp struct {
-	Type		int16
-	Pad_cgo_0	[2]byte
-	Pid		int32
-	Line		[32]int8
-	Id		[4]int8
-	User		[32]int8
-	Host		[256]int8
-	Exit		exit_status
-	Session		int32
-	Tv		UtTv
-	Addr_v6		[4]int32
-	X__unused	[20]int8
+	Type      int16
+	Pad_cgo_0 [2]byte
+	Pid       int32
+	Line      [32]int8
+	Id        [4]int8
+	User      [32]int8
+	Host      [256]int8
+	Exit      exit_status
+	Session   int32
+	Tv        UtTv
+	Addr_v6   [4]int32
+	X__unused [20]int8
 }
 type exit_status struct {
-	Termination	int16
-	Exit		int16
+	Termination int16
+	Exit        int16
 }
 type UtTv struct {
-	TvSec	int32
-	TvUsec	int32
+	TvSec  int32
+	TvUsec int32
 }
diff --git a/common/common.go b/internal/common/common.go
similarity index 88%
rename from common/common.go
rename to internal/common/common.go
index d04cdfd7f..aeadda6b2 100644
--- a/common/common.go
+++ b/internal/common/common.go
@@ -14,6 +14,7 @@ import (
 	"os"
 	"os/exec"
 	"path"
+	"path/filepath"
 	"reflect"
 	"runtime"
 	"strconv"
@@ -209,10 +210,30 @@ func PathExists(filename string) bool {
 }
 
 //GetEnv retreives the environment variable key. If it does not exist it returns the default.
-func GetEnv(key string, dfault string) string {
+func GetEnv(key string, dfault string, combineWith ...string) string {
 	value := os.Getenv(key)
 	if value == "" {
 		value = dfault
 	}
-	return value
+
+	switch len(combineWith) {
+	case 0:
+		return value
+	case 1:
+		return filepath.Join(value, combineWith[0])
+	default:
+		all := make([]string, len(combineWith)+1)
+		all[0] = value
+		copy(all[1:], combineWith)
+		return filepath.Join(all...)
+	}
+	panic("invalid switch case")
+}
+
+func HostProc(combineWith ...string) string {
+	return GetEnv("HOST_PROC", "/proc", combineWith...)
+}
+
+func HostSys(combineWith ...string) string {
+	return GetEnv("HOST_SYS", "/sys", combineWith...)
 }
diff --git a/common/common_darwin.go b/internal/common/common_darwin.go
similarity index 100%
rename from common/common_darwin.go
rename to internal/common/common_darwin.go
diff --git a/common/common_freebsd.go b/internal/common/common_freebsd.go
similarity index 99%
rename from common/common_freebsd.go
rename to internal/common/common_freebsd.go
index 3c1124655..8ccd40e90 100644
--- a/common/common_freebsd.go
+++ b/internal/common/common_freebsd.go
@@ -3,9 +3,9 @@
 package common
 
 import (
-	"syscall"
 	"os/exec"
 	"strings"
+	"syscall"
 	"unsafe"
 )
 
@@ -58,4 +58,3 @@ func CallSyscall(mib []int32) ([]byte, uint64, error) {
 
 	return buf, length, nil
 }
-
diff --git a/common/common_linux.go b/internal/common/common_linux.go
similarity index 100%
rename from common/common_linux.go
rename to internal/common/common_linux.go
diff --git a/common/common_test.go b/internal/common/common_test.go
similarity index 100%
rename from common/common_test.go
rename to internal/common/common_test.go
diff --git a/common/common_unix.go b/internal/common/common_unix.go
similarity index 100%
rename from common/common_unix.go
rename to internal/common/common_unix.go
diff --git a/common/common_windows.go b/internal/common/common_windows.go
similarity index 100%
rename from common/common_windows.go
rename to internal/common/common_windows.go
diff --git a/load/load_linux.go b/load/load_linux.go
index 4ab5a9686..80621c966 100644
--- a/load/load_linux.go
+++ b/load/load_linux.go
@@ -7,11 +7,11 @@ import (
 	"strconv"
 	"strings"
 
-	common "github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 func LoadAvg() (*LoadAvgStat, error) {
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/loadavg"
+	filename := common.HostProc("loadavg")
 	line, err := ioutil.ReadFile(filename)
 	if err != nil {
 		return nil, err
diff --git a/mem/mem_linux.go b/mem/mem_linux.go
index e45a0842d..fc9226219 100644
--- a/mem/mem_linux.go
+++ b/mem/mem_linux.go
@@ -7,11 +7,11 @@ import (
 	"strings"
 	"syscall"
 
-	common "github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 func VirtualMemory() (*VirtualMemoryStat, error) {
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/meminfo"
+	filename := common.HostProc("meminfo")
 	lines, _ := common.ReadLines(filename)
 	// flag if MemAvailable is in /proc/meminfo (kernel 3.14+)
 	memavail := false
@@ -74,7 +74,7 @@ func SwapMemory() (*SwapMemoryStat, error) {
 	} else {
 		ret.UsedPercent = 0
 	}
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/vmstat"
+	filename := common.HostProc("vmstat")
 	lines, _ := common.ReadLines(filename)
 	for _, l := range lines {
 		fields := strings.Fields(l)
diff --git a/net/net.go b/net/net.go
index 506fe57e0..e8a1035a9 100644
--- a/net/net.go
+++ b/net/net.go
@@ -8,7 +8,7 @@ import (
 	"strings"
 	"syscall"
 
-	"github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 var invoke common.Invoker
diff --git a/net/net_linux.go b/net/net_linux.go
index 73b2bee6c..421837302 100644
--- a/net/net_linux.go
+++ b/net/net_linux.go
@@ -6,7 +6,7 @@ import (
 	"strconv"
 	"strings"
 
-	common "github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 // NetIOCounters returnes network I/O statistics for every network
@@ -15,7 +15,7 @@ import (
 // every network interface installed on the system is returned
 // separately.
 func NetIOCounters(pernic bool) ([]NetIOCountersStat, error) {
-	filename := common.GetEnv("HOST_PROC", "/proc") + "/net/dev"
+	filename := common.HostProc("net/dev")
 	lines, err := common.ReadLines(filename)
 	if err != nil {
 		return nil, err
diff --git a/net/net_unix.go b/net/net_unix.go
index 0b8a844e7..fe2f1eb4d 100644
--- a/net/net_unix.go
+++ b/net/net_unix.go
@@ -5,7 +5,7 @@ package net
 import (
 	"strings"
 
-	"github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 // Return a list of network connections opened.
diff --git a/process/process.go b/process/process.go
index abe522c80..0526f78a7 100644
--- a/process/process.go
+++ b/process/process.go
@@ -5,8 +5,8 @@ import (
 	"runtime"
 	"time"
 
-	"github.com/shirou/gopsutil/common"
 	"github.com/shirou/gopsutil/cpu"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 var invoke common.Invoker
diff --git a/process/process_linux.go b/process/process_linux.go
index 0d3a3973e..9855b74a6 100644
--- a/process/process_linux.go
+++ b/process/process_linux.go
@@ -12,9 +12,9 @@ import (
 	"strings"
 	"syscall"
 
-	"github.com/shirou/gopsutil/common"
 	"github.com/shirou/gopsutil/cpu"
 	"github.com/shirou/gopsutil/host"
+	"github.com/shirou/gopsutil/internal/common"
 	"github.com/shirou/gopsutil/net"
 )
 
@@ -222,7 +222,7 @@ func (p *Process) IsRunning() (bool, error) {
 func (p *Process) MemoryMaps(grouped bool) (*[]MemoryMapsStat, error) {
 	pid := p.Pid
 	var ret []MemoryMapsStat
-	smapsPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "smaps")
+	smapsPath := common.HostProc(strconv.Itoa(int(pid)), "smaps")
 	contents, err := ioutil.ReadFile(smapsPath)
 	if err != nil {
 		return nil, err
@@ -303,7 +303,7 @@ func (p *Process) MemoryMaps(grouped bool) (*[]MemoryMapsStat, error) {
 // Get num_fds from /proc/(pid)/fd
 func (p *Process) fillFromfd() (int32, []*OpenFilesStat, error) {
 	pid := p.Pid
-	statPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "fd")
+	statPath := common.HostProc(strconv.Itoa(int(pid)), "fd")
 	d, err := os.Open(statPath)
 	if err != nil {
 		return 0, nil, err
@@ -336,7 +336,7 @@ func (p *Process) fillFromfd() (int32, []*OpenFilesStat, error) {
 // Get cwd from /proc/(pid)/cwd
 func (p *Process) fillFromCwd() (string, error) {
 	pid := p.Pid
-	cwdPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "cwd")
+	cwdPath := common.HostProc(strconv.Itoa(int(pid)), "cwd")
 	cwd, err := os.Readlink(cwdPath)
 	if err != nil {
 		return "", err
@@ -347,7 +347,7 @@ func (p *Process) fillFromCwd() (string, error) {
 // Get exe from /proc/(pid)/exe
 func (p *Process) fillFromExe() (string, error) {
 	pid := p.Pid
-	exePath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "exe")
+	exePath := common.HostProc(strconv.Itoa(int(pid)), "exe")
 	exe, err := os.Readlink(exePath)
 	if err != nil {
 		return "", err
@@ -358,7 +358,7 @@ func (p *Process) fillFromExe() (string, error) {
 // Get cmdline from /proc/(pid)/cmdline
 func (p *Process) fillFromCmdline() (string, error) {
 	pid := p.Pid
-	cmdPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "cmdline")
+	cmdPath := common.HostProc(strconv.Itoa(int(pid)), "cmdline")
 	cmdline, err := ioutil.ReadFile(cmdPath)
 	if err != nil {
 		return "", err
@@ -376,7 +376,7 @@ func (p *Process) fillFromCmdline() (string, error) {
 // Get IO status from /proc/(pid)/io
 func (p *Process) fillFromIO() (*IOCountersStat, error) {
 	pid := p.Pid
-	ioPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "io")
+	ioPath := common.HostProc(strconv.Itoa(int(pid)), "io")
 	ioline, err := ioutil.ReadFile(ioPath)
 	if err != nil {
 		return nil, err
@@ -415,7 +415,7 @@ func (p *Process) fillFromIO() (*IOCountersStat, error) {
 // Get memory info from /proc/(pid)/statm
 func (p *Process) fillFromStatm() (*MemoryInfoStat, *MemoryInfoExStat, error) {
 	pid := p.Pid
-	memPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "statm")
+	memPath := common.HostProc(strconv.Itoa(int(pid)), "statm")
 	contents, err := ioutil.ReadFile(memPath)
 	if err != nil {
 		return nil, nil, err
@@ -467,7 +467,7 @@ func (p *Process) fillFromStatm() (*MemoryInfoStat, *MemoryInfoExStat, error) {
 // Get various status from /proc/(pid)/status
 func (p *Process) fillFromStatus() error {
 	pid := p.Pid
-	statPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "status")
+	statPath := common.HostProc(strconv.Itoa(int(pid)), "status")
 	contents, err := ioutil.ReadFile(statPath)
 	if err != nil {
 		return err
@@ -554,7 +554,7 @@ func (p *Process) fillFromStatus() error {
 
 func (p *Process) fillFromStat() (string, int32, *cpu.CPUTimesStat, int64, int32, error) {
 	pid := p.Pid
-	statPath := filepath.Join(common.GetEnv("HOST_PROC", "/proc"), strconv.Itoa(int(pid)), "stat")
+	statPath := common.HostProc(strconv.Itoa(int(pid)), "stat")
 	contents, err := ioutil.ReadFile(statPath)
 	if err != nil {
 		return "", 0, nil, 0, 0, err
@@ -610,7 +610,7 @@ func (p *Process) fillFromStat() (string, int32, *cpu.CPUTimesStat, int64, int32
 func Pids() ([]int32, error) {
 	var ret []int32
 
-	d, err := os.Open(common.GetEnv("HOST_PROC", "/proc"))
+	d, err := os.Open(common.HostProc())
 	if err != nil {
 		return nil, err
 	}
diff --git a/process/process_test.go b/process/process_test.go
index 854d63c12..4cb475a19 100644
--- a/process/process_test.go
+++ b/process/process_test.go
@@ -8,7 +8,7 @@ import (
 	"testing"
 	"time"
 
-	"github.com/shirou/gopsutil/common"
+	"github.com/shirou/gopsutil/internal/common"
 )
 
 var mu sync.Mutex