diff --git a/reflect/protoregistry/registry.go b/reflect/protoregistry/registry.go
index a4df65b..cba713f 100644
--- a/reflect/protoregistry/registry.go
+++ b/reflect/protoregistry/registry.go
@@ -20,6 +20,7 @@
 	"log"
 	"reflect"
 	"strings"
+	"sync"
 
 	"google.golang.org/protobuf/internal/errors"
 	"google.golang.org/protobuf/reflect/protoreflect"
@@ -37,6 +38,8 @@
 	return true
 }
 
+var globalMutex sync.RWMutex
+
 // GlobalFiles is a global registry of file descriptors.
 var GlobalFiles *Files = new(Files)
 
@@ -87,6 +90,10 @@
 //
 // It is permitted for multiple files to have the same file path.
 func (r *Files) Register(files ...protoreflect.FileDescriptor) error {
+	if r == GlobalFiles {
+		globalMutex.Lock()
+		defer globalMutex.Unlock()
+	}
 	if r.descsByName == nil {
 		r.descsByName = map[protoreflect.FullName]interface{}{
 			"": &packageDescriptor{},
@@ -161,6 +168,10 @@
 	if r == nil {
 		return nil, NotFound
 	}
+	if r == GlobalFiles {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	prefix := name
 	suffix := nameSuffix("")
 	for prefix != "" {
@@ -249,6 +260,10 @@
 	if r == nil {
 		return nil, NotFound
 	}
+	if r == GlobalFiles {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	if fd, ok := r.filesByPath[path]; ok {
 		return fd, nil
 	}
@@ -260,6 +275,10 @@
 	if r == nil {
 		return 0
 	}
+	if r == GlobalFiles {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	return len(r.filesByPath)
 }
 
@@ -269,6 +288,10 @@
 	if r == nil {
 		return
 	}
+	if r == GlobalFiles {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	for _, file := range r.filesByPath {
 		if !f(file) {
 			return
@@ -281,6 +304,10 @@
 	if r == nil {
 		return 0
 	}
+	if r == GlobalFiles {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	p, ok := r.descsByName[name].(*packageDescriptor)
 	if !ok {
 		return 0
@@ -294,6 +321,10 @@
 	if r == nil {
 		return
 	}
+	if r == GlobalFiles {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	p, ok := r.descsByName[name].(*packageDescriptor)
 	if !ok {
 		return
@@ -441,6 +472,10 @@
 // (e.g., two different types have the same full name),
 // then the first type takes precedence and an error is returned.
 func (r *Types) Register(typs ...Type) error {
+	if r == GlobalTypes {
+		globalMutex.Lock()
+		defer globalMutex.Unlock()
+	}
 	var firstErr error
 typeLoop:
 	for _, typ := range typs {
@@ -525,6 +560,10 @@
 	if r == nil {
 		return nil, NotFound
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	if v := r.typesByName[enum]; v != nil {
 		if et, _ := v.(protoreflect.EnumType); et != nil {
 			return et, nil
@@ -551,6 +590,10 @@
 	if r == nil {
 		return nil, NotFound
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	message := protoreflect.FullName(url)
 	if i := strings.LastIndexByte(url, '/'); i >= 0 {
 		message = message[i+len("/"):]
@@ -575,6 +618,10 @@
 	if r == nil {
 		return nil, NotFound
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	if v := r.typesByName[field]; v != nil {
 		if xt, _ := v.(protoreflect.ExtensionType); xt != nil {
 			return xt, nil
@@ -592,6 +639,10 @@
 	if r == nil {
 		return nil, NotFound
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	if xt, ok := r.extensionsByMessage[message][field]; ok {
 		return xt, nil
 	}
@@ -603,6 +654,10 @@
 	if r == nil {
 		return 0
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	return r.numEnums
 }
 
@@ -612,6 +667,10 @@
 	if r == nil {
 		return
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	for _, typ := range r.typesByName {
 		if et, ok := typ.(protoreflect.EnumType); ok {
 			if !f(et) {
@@ -626,6 +685,10 @@
 	if r == nil {
 		return 0
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	return r.numMessages
 }
 
@@ -635,6 +698,10 @@
 	if r == nil {
 		return
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	for _, typ := range r.typesByName {
 		if mt, ok := typ.(protoreflect.MessageType); ok {
 			if !f(mt) {
@@ -649,6 +716,10 @@
 	if r == nil {
 		return 0
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	return r.numExtensions
 }
 
@@ -658,6 +729,10 @@
 	if r == nil {
 		return
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	for _, typ := range r.typesByName {
 		if xt, ok := typ.(protoreflect.ExtensionType); ok {
 			if !f(xt) {
@@ -673,6 +748,10 @@
 	if r == nil {
 		return 0
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	return len(r.extensionsByMessage[message])
 }
 
@@ -682,6 +761,10 @@
 	if r == nil {
 		return
 	}
+	if r == GlobalTypes {
+		globalMutex.RLock()
+		defer globalMutex.RUnlock()
+	}
 	for _, xt := range r.extensionsByMessage[message] {
 		if !f(xt) {
 			return