diff --git a/backend/app/cmd/server.go b/backend/app/cmd/server.go
index d568c2a8..21707357 100644
--- a/backend/app/cmd/server.go
+++ b/backend/app/cmd/server.go
@@ -718,13 +718,17 @@ func (s *ServerCommand) addAuthProviders(authenticator *auth.Service) error {
 
 	if s.Auth.Anonymous {
 		log.Print("[INFO] anonymous access enabled")
-		var isValidAnonName = regexp.MustCompile(`^[a-zA-Z][\w ]+$`).MatchString
+		var isValidAnonName = regexp.MustCompile(`^[\p{L}\d_ ]+$`).MatchString
 		authenticator.AddDirectProvider("anonymous", provider.CredCheckerFunc(func(user, _ string) (ok bool, err error) {
 			user = strings.TrimSpace(user)
 			if len(user) < 3 {
 				log.Printf("[WARN] name %q is too short, should be at least 3 characters", user)
 				return false, nil
 			}
+			if len(user) > 64 {
+				log.Printf("[WARN] name %q is too long, should be up to 64 characters", user)
+				return false, nil
+			}
 
 			if !isValidAnonName(user) {
 				log.Printf("[WARN] name %q should have letters, digits, underscores and spaces only", user)
diff --git a/backend/app/cmd/server_test.go b/backend/app/cmd/server_test.go
index defbcc85..12c4d582 100644
--- a/backend/app/cmd/server_test.go
+++ b/backend/app/cmd/server_test.go
@@ -133,6 +133,12 @@ func TestServerApp_AnonMode(t *testing.T) {
 	defer resp.Body.Close()
 	assert.Equal(t, http.StatusCreated, resp.StatusCode)
 
+	// try to login with non-latin name
+	resp, err = http.Get(fmt.Sprintf("http://localhost:%d/auth/anonymous/login?user=Раз_Два%20%20Три_34567&aud=remark", port))
+	require.NoError(t, err)
+	defer resp.Body.Close()
+	assert.Equal(t, http.StatusOK, resp.StatusCode)
+
 	// try to login with bad name
 	resp, err = http.Get(fmt.Sprintf("http://localhost:%d/auth/anonymous/login?user=**blah123&aud=remark", port))
 	require.NoError(t, err)
@@ -145,6 +151,13 @@ func TestServerApp_AnonMode(t *testing.T) {
 	defer resp.Body.Close()
 	assert.Equal(t, http.StatusForbidden, resp.StatusCode)
 
+	// try to login with long name
+	ln := strings.Repeat("x", 65)
+	resp, err = http.Get(fmt.Sprintf("http://localhost:%d/auth/anonymous/login?user=%s&aud=remark", port, ln))
+	require.NoError(t, err)
+	defer resp.Body.Close()
+	assert.Equal(t, http.StatusForbidden, resp.StatusCode)
+
 	// try to login with admin name
 	resp, err = http.Get(fmt.Sprintf("http://localhost:%d/auth/anonymous/login?user=umputun&aud=remark", port))
 	require.NoError(t, err)