diff --git a/pkg/client/rp/relying_party.go b/pkg/client/rp/relying_party.go
index ac7f4663..029a897c 100644
--- a/pkg/client/rp/relying_party.go
+++ b/pkg/client/rp/relying_party.go
@@ -734,11 +734,11 @@ func (t tokenEndpointCaller) TokenEndpoint() string {
 
 type RefreshTokenRequest struct {
 	RefreshToken        string                   `schema:"refresh_token"`
-	Scopes              oidc.SpaceDelimitedArray `schema:"scope"`
-	ClientID            string                   `schema:"client_id"`
-	ClientSecret        string                   `schema:"client_secret"`
-	ClientAssertion     string                   `schema:"client_assertion"`
-	ClientAssertionType string                   `schema:"client_assertion_type"`
+	Scopes              oidc.SpaceDelimitedArray `schema:"scope,omitempty"`
+	ClientID            string                   `schema:"client_id,omitempty"`
+	ClientSecret        string                   `schema:"client_secret,omitempty"`
+	ClientAssertion     string                   `schema:"client_assertion,omitempty"`
+	ClientAssertionType string                   `schema:"client_assertion_type,omitempty"`
 	GrantType           oidc.GrantType           `schema:"grant_type"`
 }