diff --git a/pkg/oidc/token_request.go b/pkg/oidc/token_request.go
index dadb205..1de1890 100644
--- a/pkg/oidc/token_request.go
+++ b/pkg/oidc/token_request.go
@@ -240,6 +240,6 @@ type ClientCredentialsRequest struct {
 	Scope               SpaceDelimitedArray `schema:"scope"`
 	ClientID            string              `schema:"client_id"`
 	ClientSecret        string              `schema:"client_secret"`
-	ClientAssertion     string              `schema:"client_assertion"`
-	ClientAssertionType string              `schema:"client_assertion_type"`
+	ClientAssertion     string              `schema:"client_assertion,omitempty"`
+	ClientAssertionType string              `schema:"client_assertion_type,omitempty"`
 }