diff --git a/process/process.go b/process/process.go
index a7d04f4..c674b3d 100644
--- a/process/process.go
+++ b/process/process.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"math"
 	"runtime"
+	"sort"
 	"time"
 
 	"github.com/shirou/gopsutil/cpu"
@@ -14,9 +15,9 @@ import (
 )
 
 var (
-	invoke          common.Invoker = common.Invoke{}
-	ErrorNoChildren                = errors.New("process does not have children")
-	ErrorProcessNotRunning         = errors.New("process does not exist")
+	invoke                 common.Invoker = common.Invoke{}
+	ErrorNoChildren                       = errors.New("process does not have children")
+	ErrorProcessNotRunning                = errors.New("process does not exist")
 )
 
 type Process struct {
@@ -137,6 +138,17 @@ func (p NumCtxSwitchesStat) String() string {
 	return string(s)
 }
 
+// Pids returns a slice of process ID list which are running now.
+func Pids() ([]int32, error) {
+	return PidsWithContext(context.Background())
+}
+
+func PidsWithContext(ctx context.Context) ([]int32, error) {
+	pids, err := pidsWithContext(ctx)
+	sort.Slice(pids, func(i, j int) bool { return pids[i] < pids[j] })
+	return pids, err
+}
+
 // NewProcess creates a new Process instance, it only stores the pid and
 // checks that the process exists. Other method on Process can be used
 // to get more information about the process. An error will be returned
diff --git a/process/process_darwin.go b/process/process_darwin.go
index ad7354b..98a5566 100644
--- a/process/process_darwin.go
+++ b/process/process_darwin.go
@@ -44,11 +44,7 @@ type MemoryInfoExStat struct {
 type MemoryMapsStat struct {
 }
 
-func Pids() ([]int32, error) {
-	return PidsWithContext(context.Background())
-}
-
-func PidsWithContext(ctx context.Context) ([]int32, error) {
+func pidsWithContext(ctx context.Context) ([]int32, error) {
 	var ret []int32
 
 	pids, err := callPsWithContext(ctx, "pid", 0, false)
diff --git a/process/process_fallback.go b/process/process_fallback.go
index 76f7caa..3201efd 100644
--- a/process/process_fallback.go
+++ b/process/process_fallback.go
@@ -28,11 +28,7 @@ type MemoryMapsStat struct {
 type MemoryInfoExStat struct {
 }
 
-func Pids() ([]int32, error) {
-	return PidsWithContext(context.Background())
-}
-
-func PidsWithContext(ctx context.Context) ([]int32, error) {
+func pidsWithContext(ctx context.Context) ([]int32, error) {
 	return []int32{}, common.ErrNotImplementedError
 }
 
diff --git a/process/process_freebsd.go b/process/process_freebsd.go
index d606615..0d4bbfc 100644
--- a/process/process_freebsd.go
+++ b/process/process_freebsd.go
@@ -23,11 +23,7 @@ type MemoryInfoExStat struct {
 type MemoryMapsStat struct {
 }
 
-func Pids() ([]int32, error) {
-	return PidsWithContext(context.Background())
-}
-
-func PidsWithContext(ctx context.Context) ([]int32, error) {
+func pidsWithContext(ctx context.Context) ([]int32, error) {
 	var ret []int32
 	procs, err := Processes()
 	if err != nil {
diff --git a/process/process_linux.go b/process/process_linux.go
index 9d9b09e..062b0ae 100644
--- a/process/process_linux.go
+++ b/process/process_linux.go
@@ -1280,12 +1280,7 @@ func (p *Process) fillFromStatWithContext(ctx context.Context) (uint64, int32, *
 	return p.fillFromTIDStat(-1)
 }
 
-// Pids returns a slice of process ID list which are running now.
-func Pids() ([]int32, error) {
-	return PidsWithContext(context.Background())
-}
-
-func PidsWithContext(ctx context.Context) ([]int32, error) {
+func pidsWithContext(ctx context.Context) ([]int32, error) {
 	return readPidsFromDir(common.HostProc())
 }
 
diff --git a/process/process_openbsd.go b/process/process_openbsd.go
index f95e750..56e3500 100644
--- a/process/process_openbsd.go
+++ b/process/process_openbsd.go
@@ -26,11 +26,7 @@ type MemoryInfoExStat struct {
 type MemoryMapsStat struct {
 }
 
-func Pids() ([]int32, error) {
-	return PidsWithContext(context.Background())
-}
-
-func PidsWithContext(ctx context.Context) ([]int32, error) {
+func pidsWithContext(ctx context.Context) ([]int32, error) {
 	var ret []int32
 	procs, err := Processes()
 	if err != nil {
diff --git a/process/process_windows.go b/process/process_windows.go
index 7a6a9de..f78c9be 100644
--- a/process/process_windows.go
+++ b/process/process_windows.go
@@ -150,11 +150,7 @@ func init() {
 		0)
 }
 
-func Pids() ([]int32, error) {
-	return PidsWithContext(context.Background())
-}
-
-func PidsWithContext(ctx context.Context) ([]int32, error) {
+func pidsWithContext(ctx context.Context) ([]int32, error) {
 	// inspired by https://gist.github.com/henkman/3083408
 	// and https://github.com/giampaolo/psutil/blob/1c3a15f637521ba5c0031283da39c733fda53e4c/psutil/arch/windows/process_info.c#L315-L329
 	var ret []int32