diff --git a/examples/server-auth/main.go b/examples/server-auth/main.go
index b15901c9..1104b580 100644
--- a/examples/server-auth/main.go
+++ b/examples/server-auth/main.go
@@ -147,6 +147,9 @@ func (sh *serverHandler) OnSetup(ctx *gortsplib.ServerHandlerOnSetupCtx) (*base.
 		}
 	}
 
+	sh.mutex.Lock()
+	defer sh.mutex.Unlock()
+
 	// no one is publishing yet
 	if sh.stream == nil {
 		return &base.Response{
diff --git a/examples/server-tls/main.go b/examples/server-tls/main.go
index 751f1d83..03a899ec 100644
--- a/examples/server-tls/main.go
+++ b/examples/server-tls/main.go
@@ -108,6 +108,9 @@ func (sh *serverHandler) OnAnnounce(ctx *gortsplib.ServerHandlerOnAnnounceCtx) (
 func (sh *serverHandler) OnSetup(ctx *gortsplib.ServerHandlerOnSetupCtx) (*base.Response, *gortsplib.ServerStream, error) {
 	log.Printf("setup request")
 
+	sh.mutex.Lock()
+	defer sh.mutex.Unlock()
+
 	// no one is publishing yet
 	if sh.stream == nil {
 		return &base.Response{
diff --git a/examples/server/main.go b/examples/server/main.go
index 2ecca102..5c875cc3 100644
--- a/examples/server/main.go
+++ b/examples/server/main.go
@@ -107,6 +107,9 @@ func (sh *serverHandler) OnAnnounce(ctx *gortsplib.ServerHandlerOnAnnounceCtx) (
 func (sh *serverHandler) OnSetup(ctx *gortsplib.ServerHandlerOnSetupCtx) (*base.Response, *gortsplib.ServerStream, error) {
 	log.Printf("setup request")
 
+	sh.mutex.Lock()
+	defer sh.mutex.Unlock()
+
 	// no one is publishing yet
 	if sh.stream == nil {
 		return &base.Response{