diff --git a/pkg/etw/eventopt.go b/pkg/etw/eventopt.go
index 0a8386d..a0a8176 100644
--- a/pkg/etw/eventopt.go
+++ b/pkg/etw/eventopt.go
@@ -1,13 +1,13 @@
 package etw
 
 import (
-	"golang.org/x/sys/windows"
+	"github.com/Microsoft/go-winio/pkg/guid"
 )
 
 type eventOptions struct {
 	descriptor        *eventDescriptor
-	activityID        *windows.GUID
-	relatedActivityID *windows.GUID
+	activityID        *guid.GUID
+	relatedActivityID *guid.GUID
 	tags              uint32
 }
 
@@ -59,14 +59,14 @@ func WithTags(newTags uint32) EventOpt {
 }
 
 // WithActivityID specifies the activity ID of the event to be written.
-func WithActivityID(activityID *windows.GUID) EventOpt {
+func WithActivityID(activityID *guid.GUID) EventOpt {
 	return func(options *eventOptions) {
 		options.activityID = activityID
 	}
 }
 
 // WithRelatedActivityID specifies the parent activity ID of the event to be written.
-func WithRelatedActivityID(activityID *windows.GUID) EventOpt {
+func WithRelatedActivityID(activityID *guid.GUID) EventOpt {
 	return func(options *eventOptions) {
 		options.relatedActivityID = activityID
 	}
diff --git a/pkg/etw/provider.go b/pkg/etw/provider.go
index 88eb75f..7a3c13d 100644
--- a/pkg/etw/provider.go
+++ b/pkg/etw/provider.go
@@ -4,12 +4,11 @@ import (
 	"bytes"
 	"crypto/sha1"
 	"encoding/binary"
-	"encoding/hex"
-	"fmt"
 	"strings"
 	"unicode/utf16"
 	"unsafe"
 
+	"github.com/Microsoft/go-winio/pkg/guid"
 	"golang.org/x/sys/windows"
 )
 
@@ -17,7 +16,7 @@ import (
 // name and ID (GUID), which should always have a 1:1 mapping to each other
 // (e.g. don't use multiple provider names with the same ID, or vice versa).
 type Provider struct {
-	ID         *windows.GUID
+	ID         *guid.GUID
 	handle     providerHandle
 	metadata   []byte
 	callback   EnableCallback
@@ -30,19 +29,7 @@ type Provider struct {
 
 // String returns the `provider`.ID as a string
 func (provider *Provider) String() string {
-	data1 := make([]byte, 4)
-	binary.BigEndian.PutUint32(data1, provider.ID.Data1)
-	data2 := make([]byte, 2)
-	binary.BigEndian.PutUint16(data2, provider.ID.Data2)
-	data3 := make([]byte, 2)
-	binary.BigEndian.PutUint16(data3, provider.ID.Data3)
-	return fmt.Sprintf(
-		"%s-%s-%s-%s-%s",
-		hex.EncodeToString(data1),
-		hex.EncodeToString(data2),
-		hex.EncodeToString(data3),
-		hex.EncodeToString(provider.ID.Data4[:2]),
-		hex.EncodeToString(provider.ID.Data4[2:]))
+	return provider.ID.String()
 }
 
 type providerHandle windows.Handle
@@ -72,9 +59,9 @@ const (
 
 // EnableCallback is the form of the callback function that receives provider
 // enable/disable notifications from ETW.
-type EnableCallback func(*windows.GUID, ProviderState, Level, uint64, uint64, uintptr)
+type EnableCallback func(*guid.GUID, ProviderState, Level, uint64, uint64, uintptr)
 
-func providerCallback(sourceID *windows.GUID, state ProviderState, level Level, matchAnyKeyword uint64, matchAllKeyword uint64, filterData uintptr, i uintptr) {
+func providerCallback(sourceID *guid.GUID, state ProviderState, level Level, matchAnyKeyword uint64, matchAllKeyword uint64, filterData uintptr, i uintptr) {
 	provider := providers.getProvider(uint(i))
 
 	switch state {
@@ -96,7 +83,7 @@ func providerCallback(sourceID *windows.GUID, state ProviderState, level Level,
 // for provider notifications. Because Go has trouble with callback arguments of
 // different size, it has only pointer-sized arguments, which are then cast to
 // the appropriate types when calling providerCallback.
-func providerCallbackAdapter(sourceID *windows.GUID, state uintptr, level uintptr, matchAnyKeyword uintptr, matchAllKeyword uintptr, filterData uintptr, i uintptr) uintptr {
+func providerCallbackAdapter(sourceID *guid.GUID, state uintptr, level uintptr, matchAnyKeyword uintptr, matchAllKeyword uintptr, filterData uintptr, i uintptr) uintptr {
 	providerCallback(sourceID, ProviderState(state), Level(level), uint64(matchAnyKeyword), uint64(matchAllKeyword), filterData, i)
 	return 0
 }
@@ -108,7 +95,7 @@ func providerCallbackAdapter(sourceID *windows.GUID, state uintptr, level uintpt
 // The algorithm is roughly:
 // Hash = Sha1(namespace + arg.ToUpper().ToUtf16be())
 // Guid = Hash[0..15], with Hash[7] tweaked according to RFC 4122
-func providerIDFromName(name string) *windows.GUID {
+func providerIDFromName(name string) *guid.GUID {
 	buffer := sha1.New()
 
 	namespace := []byte{0x48, 0x2C, 0x2D, 0xB2, 0xC3, 0x90, 0x47, 0xC8, 0x87, 0xF8, 0x1A, 0x15, 0xBF, 0xC1, 0x30, 0xFB}
@@ -119,7 +106,7 @@ func providerIDFromName(name string) *windows.GUID {
 	sum := buffer.Sum(nil)
 	sum[7] = (sum[7] & 0xf) | 0x50
 
-	return &windows.GUID{
+	return &guid.GUID{
 		Data1: binary.LittleEndian.Uint32(sum[0:4]),
 		Data2: binary.LittleEndian.Uint16(sum[4:6]),
 		Data3: binary.LittleEndian.Uint16(sum[6:8]),
@@ -137,7 +124,7 @@ func NewProvider(name string, callback EnableCallback) (provider *Provider, err
 // provider ID to be manually specified. This is most useful when there is an
 // existing provider ID that must be used to conform to existing diagnostic
 // infrastructure.
-func NewProviderWithID(name string, id *windows.GUID, callback EnableCallback) (provider *Provider, err error) {
+func NewProviderWithID(name string, id *guid.GUID, callback EnableCallback) (provider *Provider, err error) {
 	providerCallbackOnce.Do(func() {
 		globalProviderCallback = windows.NewCallback(providerCallbackAdapter)
 	})
@@ -151,7 +138,7 @@ func NewProviderWithID(name string, id *windows.GUID, callback EnableCallback) (
 	provider.ID = id
 	provider.callback = callback
 
-	if err := eventRegister(provider.ID, globalProviderCallback, uintptr(provider.index), &provider.handle); err != nil {
+	if err := eventRegister((*windows.GUID)(provider.ID), globalProviderCallback, uintptr(provider.index), &provider.handle); err != nil {
 		return nil, err
 	}
 
@@ -259,8 +246,8 @@ func (provider *Provider) WriteEvent(name string, eventOpts []EventOpt, fieldOpt
 // the ETW infrastructure.
 func (provider *Provider) writeEventRaw(
 	descriptor *eventDescriptor,
-	activityID *windows.GUID,
-	relatedActivityID *windows.GUID,
+	activityID *guid.GUID,
+	relatedActivityID *guid.GUID,
 	metadataBlobs [][]byte,
 	dataBlobs [][]byte) error {
 
@@ -275,5 +262,5 @@ func (provider *Provider) writeEventRaw(
 		dataDescriptors = append(dataDescriptors, newEventDataDescriptor(eventDataDescriptorTypeUserData, blob))
 	}
 
-	return eventWriteTransfer(provider.handle, descriptor, activityID, relatedActivityID, dataDescriptorCount, &dataDescriptors[0])
+	return eventWriteTransfer(provider.handle, descriptor, (*windows.GUID)(activityID), (*windows.GUID)(relatedActivityID), dataDescriptorCount, &dataDescriptors[0])
 }
diff --git a/pkg/etw/sample/sample.go b/pkg/etw/sample/sample.go
index f9ece39..d86d43e 100644
--- a/pkg/etw/sample/sample.go
+++ b/pkg/etw/sample/sample.go
@@ -7,12 +7,11 @@ import (
 	"os"
 
 	"github.com/Microsoft/go-winio/pkg/etw"
+	"github.com/Microsoft/go-winio/pkg/guid"
 	"github.com/sirupsen/logrus"
-
-	"golang.org/x/sys/windows"
 )
 
-func callback(sourceID *windows.GUID, state etw.ProviderState, level etw.Level, matchAnyKeyword uint64, matchAllKeyword uint64, filterData uintptr) {
+func callback(sourceID *guid.GUID, state etw.ProviderState, level etw.Level, matchAnyKeyword uint64, matchAllKeyword uint64, filterData uintptr) {
 	fmt.Printf("Callback: isEnabled=%d, level=%d, matchAnyKeyword=%d\n", state, level, matchAnyKeyword)
 }
 
diff --git a/pkg/etwlogrus/hook_test.go b/pkg/etwlogrus/hook_test.go
index 26193d2..ed2f519 100644
--- a/pkg/etwlogrus/hook_test.go
+++ b/pkg/etwlogrus/hook_test.go
@@ -1,8 +1,9 @@
 package etwlogrus
 
 import (
-	"github.com/Microsoft/go-winio/pkg/etw"
 	"testing"
+
+	"github.com/Microsoft/go-winio/pkg/etw"
 )
 
 func fireEvent(t *testing.T, p *etw.Provider, name string, value interface{}) {
diff --git a/pkg/guid/guid.go b/pkg/guid/guid.go
new file mode 100644
index 0000000..cc50972
--- /dev/null
+++ b/pkg/guid/guid.go
@@ -0,0 +1,110 @@
+package guid
+
+import (
+	"crypto/rand"
+	"encoding/binary"
+	"encoding/json"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/pkg/errors"
+	"golang.org/x/sys/windows"
+)
+
+var _ = (json.Marshaler)(&GUID{})
+var _ = (json.Unmarshaler)(&GUID{})
+
+// GUID represents a GUID/UUID. It has the same structure as
+// golang.org/x/sys/windows.GUID so that it can be used with functions expecting
+// that type. It is defined as its own type so that stringification and
+// marshaling can be supported. The representation matches that used by native
+// Windows code.
+type GUID windows.GUID
+
+// NewV4 returns a new version 4 (pseudorandom) GUID, as defined by RFC 4122.
+func NewV4() (*GUID, error) {
+	var b [16]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		return nil, err
+	}
+
+	var g GUID
+	g.Data1 = binary.LittleEndian.Uint32(b[0:4])
+	g.Data2 = binary.LittleEndian.Uint16(b[4:6])
+	g.Data3 = binary.LittleEndian.Uint16(b[6:8])
+	copy(g.Data4[:], b[8:16])
+
+	g.Data3 = (g.Data3 & 0x0fff) | 0x4000   // Version 4 (randomly generated)
+	g.Data4[0] = (g.Data4[0] & 0x3f) | 0x80 // RFC4122 variant
+	return &g, nil
+}
+
+func (g *GUID) String() string {
+	return fmt.Sprintf(
+		"%08x-%04x-%04x-%04x-%012x",
+		g.Data1,
+		g.Data2,
+		g.Data3,
+		g.Data4[:2],
+		g.Data4[2:])
+}
+
+// FromString parses a string containing a GUID and returns the GUID. The only
+// format currently supported is the `xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`
+// format.
+func FromString(s string) (*GUID, error) {
+	if len(s) != 36 {
+		return nil, errors.New("invalid GUID format (length)")
+	}
+	if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
+		return nil, errors.New("invalid GUID format (dashes)")
+	}
+
+	var g GUID
+
+	data1, err := strconv.ParseUint(s[0:8], 16, 32)
+	if err != nil {
+		return nil, errors.Wrap(err, "invalid GUID format (Data1)")
+	}
+	g.Data1 = uint32(data1)
+
+	data2, err := strconv.ParseUint(s[9:13], 16, 16)
+	if err != nil {
+		return nil, errors.Wrap(err, "invalid GUID format (Data2)")
+	}
+	g.Data2 = uint16(data2)
+
+	data3, err := strconv.ParseUint(s[14:18], 16, 16)
+	if err != nil {
+		return nil, errors.Wrap(err, "invalid GUID format (Data3)")
+	}
+	g.Data3 = uint16(data3)
+
+	for i, x := range []int{19, 21, 24, 26, 28, 30, 32, 34} {
+		v, err := strconv.ParseUint(s[x:x+2], 16, 8)
+		if err != nil {
+			return nil, errors.Wrap(err, "invalid GUID format (Data4)")
+		}
+		g.Data4[i] = uint8(v)
+	}
+
+	return &g, nil
+}
+
+// MarshalJSON marshals the GUID to JSON representation and returns it as a
+// slice of bytes.
+func (g *GUID) MarshalJSON() ([]byte, error) {
+	return json.Marshal(g.String())
+}
+
+// UnmarshalJSON unmarshals a GUID from JSON representation and sets itself to
+// the unmarshaled GUID.
+func (g *GUID) UnmarshalJSON(data []byte) error {
+	g2, err := FromString(strings.Trim(string(data), "\""))
+	if err != nil {
+		return err
+	}
+	*g = *g2
+	return nil
+}
diff --git a/pkg/guid/guid_test.go b/pkg/guid/guid_test.go
new file mode 100644
index 0000000..9123cda
--- /dev/null
+++ b/pkg/guid/guid_test.go
@@ -0,0 +1,107 @@
+package guid
+
+import (
+	"encoding/json"
+	"fmt"
+	"testing"
+)
+
+func Test_New(t *testing.T) {
+	g, err := NewV4()
+	if err != nil {
+		t.Fatal(err)
+	}
+	g2, err := NewV4()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if *g == *g2 {
+		t.Fatalf("GUIDs are equal: %s, %s", g, g2)
+	}
+}
+
+func Test_FromString(t *testing.T) {
+	orig := "8e35239e-2084-490e-a3db-ab18ee0744cb"
+	g, err := FromString(orig)
+	if err != nil {
+		t.Fatal(err)
+	}
+	s := g.String()
+	if orig != s {
+		t.Fatalf("GUIDs not equal: %s, %s", orig, s)
+	}
+}
+
+func Test_MarshalJSON(t *testing.T) {
+	g, err := NewV4()
+	if err != nil {
+		t.Fatal(err)
+	}
+	j, err := json.Marshal(g)
+	if err != nil {
+		t.Fatal(err)
+	}
+	gj := fmt.Sprintf("\"%s\"", g.String())
+	if string(j) != gj {
+		t.Fatalf("JSON not equal: %s, %s", j, gj)
+	}
+}
+
+func Test_MarshalJSON_Nested(t *testing.T) {
+	type test struct {
+		G *GUID
+	}
+	g, err := NewV4()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t1 := test{g}
+	j, err := json.Marshal(t1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	gj := fmt.Sprintf("{\"G\":\"%s\"}", g.String())
+	if string(j) != gj {
+		t.Fatalf("JSON not equal: %s, %s", j, gj)
+	}
+}
+
+func Test_UnmarshalJSON(t *testing.T) {
+	g, err := NewV4()
+	if err != nil {
+		t.Fatal(err)
+	}
+	j, err := json.Marshal(g)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var g2 GUID
+	if err := json.Unmarshal(j, &g2); err != nil {
+		t.Fatal(err)
+	}
+	if *g != g2 {
+		t.Fatalf("GUIDs not equal: %s, %s", g, &g2)
+	}
+}
+
+func Test_UnmarshalJSON_Nested(t *testing.T) {
+	type test struct {
+		G *GUID
+	}
+	g, err := NewV4()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t1 := test{g}
+	j, err := json.Marshal(t1)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var t2 test
+	if err := json.Unmarshal(j, &t2); err != nil {
+		t.Fatal(err)
+	}
+	if *t1.G != *t2.G {
+		t.Fatalf("GUIDs not equal: %v, %v", t1.G, t2.G)
+	}
+}
diff --git a/tools/etw-provider-gen/main.go b/tools/etw-provider-gen/main.go
index 96b76aa..1da4657 100644
--- a/tools/etw-provider-gen/main.go
+++ b/tools/etw-provider-gen/main.go
@@ -5,7 +5,7 @@ import (
 	"fmt"
 	"os"
 
-	"github.com/Microsoft/go-winio/internal/etw"
+	"github.com/Microsoft/go-winio/pkg/etw"
 )
 
 func main() {