diff --git a/libbeat/cmd/instance/metrics.go b/libbeat/cmd/instance/metrics.go
index 910e08a8b67..d2d0f53df4a 100644
--- a/libbeat/cmd/instance/metrics.go
+++ b/libbeat/cmd/instance/metrics.go
@@ -4,7 +4,6 @@ package instance
 
 import (
 	"fmt"
-	"os"
 	"runtime"
 
 	"github.com/elastic/beats/libbeat/logp"
@@ -65,8 +64,12 @@ func reportMemStats(m monitoring.Mode, V monitoring.Visitor) {
 }
 
 func getRSSSize() (uint64, error) {
-	beatPID := os.Getpid()
-	state, err := beatProcessStats.GetOne(beatPID)
+	pid, err := process.GetSelfPid()
+	if err != nil {
+		return 0, fmt.Errorf("error getting PID for self process: %v", err)
+	}
+
+	state, err := beatProcessStats.GetOne(pid)
 	if err != nil {
 		return 0, fmt.Errorf("error retrieving process stats: %v", err)
 	}
@@ -121,8 +124,12 @@ func reportBeatCPU(_ monitoring.Mode, V monitoring.Visitor) {
 }
 
 func getCPUUsage() (float64, *process.Ticks, error) {
-	beatPID := os.Getpid()
-	state, err := beatProcessStats.GetOne(beatPID)
+	pid, err := process.GetSelfPid()
+	if err != nil {
+		return 0.0, nil, fmt.Errorf("error getting PID for self process: %v", err)
+	}
+
+	state, err := beatProcessStats.GetOne(pid)
 	if err != nil {
 		return 0.0, nil, fmt.Errorf("error retrieving process stats: %v", err)
 	}
diff --git a/libbeat/metric/system/process/process.go b/libbeat/metric/system/process/process.go
index 7d89125b942..66f3387c586 100644
--- a/libbeat/metric/system/process/process.go
+++ b/libbeat/metric/system/process/process.go
@@ -46,7 +46,7 @@ type Process struct {
 	cpuTotalPctNorm float64
 }
 
-// Stats stores the stats of preocesses on the host.
+// Stats stores the stats of processes on the host.
 type Stats struct {
 	Procs        []string
 	ProcsMap     ProcsMap
diff --git a/libbeat/metric/system/process/process_linux.go b/libbeat/metric/system/process/process_linux.go
new file mode 100644
index 00000000000..9400a43d834
--- /dev/null
+++ b/libbeat/metric/system/process/process_linux.go
@@ -0,0 +1,20 @@
+package process
+
+import (
+	"os"
+	"path"
+	"strconv"
+
+	"github.com/elastic/gosigar"
+)
+
+// GetSelfPid returns the PID for this process
+func GetSelfPid() (int, error) {
+	pid, err := os.Readlink(path.Join(gosigar.Procd, "self"))
+
+	if err != nil {
+		return 0, err
+	}
+
+	return strconv.Atoi(pid)
+}
diff --git a/libbeat/metric/system/process/process_other.go b/libbeat/metric/system/process/process_other.go
new file mode 100644
index 00000000000..f829eac1442
--- /dev/null
+++ b/libbeat/metric/system/process/process_other.go
@@ -0,0 +1,10 @@
+// +build !linux
+
+package process
+
+import "os"
+
+// GetSelfPid returns the PID for this process
+func GetSelfPid() (int, error) {
+	return os.Getpid(), nil
+}
diff --git a/libbeat/metric/system/process/process_test.go b/libbeat/metric/system/process/process_test.go
index fe989d46a89..4bd6bcf9c6b 100644
--- a/libbeat/metric/system/process/process_test.go
+++ b/libbeat/metric/system/process/process_test.go
@@ -66,6 +66,13 @@ func TestGetProcess(t *testing.T) {
 	}
 }
 
+// See https://github.com/elastic/beats/issues/6620
+func TestGetSelfPid(t *testing.T) {
+	pid, err := GetSelfPid()
+	assert.NoError(t, err)
+	assert.Equal(t, os.Getpid(), pid)
+}
+
 func TestProcState(t *testing.T) {
 	assert.Equal(t, getProcState('R'), "running")
 	assert.Equal(t, getProcState('S'), "sleeping")