diff --git a/authority/options.go b/authority/options.go
index 9594f989..9626f48e 100644
--- a/authority/options.go
+++ b/authority/options.go
@@ -47,7 +47,7 @@ func WithDatabase(db db.AuthDB) Option {
 
 // WithGetIdentityFunc sets a custom function to retrieve the identity from
 // an external resource.
-func WithGetIdentityFunc(fn func(ctx context.Context, p provisioner.Interface, email string) (*provisioner.Identity, error)) Option {
+func WithGetIdentityFunc(fn func(ctx context.Context, p provisioner.Interface, email string, usernames ...string) (*provisioner.Identity, error)) Option {
 	return func(a *Authority) error {
 		a.getIdentityFunc = fn
 		return nil
diff --git a/authority/provisioner/oidc.go b/authority/provisioner/oidc.go
index 0a85875e..787de317 100644
--- a/authority/provisioner/oidc.go
+++ b/authority/provisioner/oidc.go
@@ -389,15 +389,10 @@ func (o *OIDC) AuthorizeSSHSign(ctx context.Context, token string) ([]SignOption
 
 	// Get the identity using either the default identityFunc or one injected
 	// externally.
-	iden, err := o.getIdentityFunc(ctx, o, claims.Email)
+	iden, err := o.getIdentityFunc(ctx, o, claims.Email, claims.PreferredUsername)
 	if err != nil {
 		return nil, errs.Wrap(http.StatusInternalServerError, err, "oidc.AuthorizeSSHSign")
 	}
-	// Reuse the contains function provided for simplicity
-	if !containsAllMembers(iden.Usernames, []string{claims.PreferredUsername}) {
-		// Add preferred_username to the identity's Username
-		iden.Usernames = append(iden.Usernames, claims.PreferredUsername)
-	}
 
 	// Certificate templates.
 	data := sshutil.CreateTemplateData(sshutil.UserCert, claims.Email, iden.Usernames)
diff --git a/authority/provisioner/oidc_test.go b/authority/provisioner/oidc_test.go
index b0e2f2f4..d203516c 100644
--- a/authority/provisioner/oidc_test.go
+++ b/authority/provisioner/oidc_test.go
@@ -500,12 +500,13 @@ func TestOIDC_AuthorizeSSHSign(t *testing.T) {
 	assert.FatalError(t, p4.Init(config))
 	assert.FatalError(t, p5.Init(config))
 
-	p4.getIdentityFunc = func(ctx context.Context, p Interface, email string) (*Identity, error) {
+	p4.getIdentityFunc = func(ctx context.Context, p Interface, email string, usernames ...string) (*Identity, error) {
 		return &Identity{Usernames: []string{"max", "mariano"}}, nil
 	}
-	p5.getIdentityFunc = func(ctx context.Context, p Interface, email string) (*Identity, error) {
+	p5.getIdentityFunc = func(ctx context.Context, p Interface, email string, usernames ...string) (*Identity, error) {
 		return nil, errors.New("force")
 	}
+	// Additional test needed for empty usernames and duplicate email and usernames
 
 	t1, err := generateSimpleToken("the-issuer", p1.ClientID, &keys.Keys[0])
 	assert.FatalError(t, err)
diff --git a/authority/provisioner/provisioner.go b/authority/provisioner/provisioner.go
index aed1900a..8cf42953 100644
--- a/authority/provisioner/provisioner.go
+++ b/authority/provisioner/provisioner.go
@@ -337,10 +337,10 @@ type Permissions struct {
 }
 
 // GetIdentityFunc is a function that returns an identity.
-type GetIdentityFunc func(ctx context.Context, p Interface, email string) (*Identity, error)
+type GetIdentityFunc func(ctx context.Context, p Interface, email string, usernames ...string) (*Identity, error)
 
 // DefaultIdentityFunc return a default identity depending on the provisioner type.
-func DefaultIdentityFunc(ctx context.Context, p Interface, email string) (*Identity, error) {
+func DefaultIdentityFunc(ctx context.Context, p Interface, email string, usernames ...string) (*Identity, error) {
 	switch k := p.(type) {
 	case *OIDC:
 		// OIDC principals would be:
@@ -351,13 +351,14 @@ func DefaultIdentityFunc(ctx context.Context, p Interface, email string) (*Ident
 		if !sshUserRegex.MatchString(name) {
 			return nil, errors.Errorf("invalid principal '%s' from email '%s'", name, email)
 		}
-		usernames := []string{name}
+		usernames := append(usernames, name)
 		if i := strings.LastIndex(email, "@"); i >= 0 {
 			if local := email[:i]; !strings.EqualFold(local, name) {
 				usernames = append(usernames, local)
 			}
 		}
 		usernames = append(usernames, email)
+		// Some remove duplicate function should be added
 		return &Identity{
 			Usernames: usernames,
 		}, nil