diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 46a6a49..41e7729 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1444,6 +1444,24 @@
 }
 
 /*
+ * State Handler : MBEDTLS_SSL_SERVER_CERTIFICATE
+ */
+int ssl_tls13_write_server_certificate( mbedtls_ssl_context *ssl )
+{
+    ((void) ssl);
+    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+}
+
+/*
+ * State Handler : MBEDTLS_SSL_CERTIFICATE_VERIFY
+ */
+int ssl_tls13_write_certificate_verify( mbedtls_ssl_context *ssl )
+{
+    ((void) ssl);
+    return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
+}
+
+/*
  * TLS 1.3 State Machine -- server side
  */
 int mbedtls_ssl_tls13_handshake_server_step( mbedtls_ssl_context *ssl )
@@ -1499,6 +1517,14 @@
             break;
 #endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
 
+        case MBEDTLS_SSL_SERVER_CERTIFICATE:
+            ret = ssl_tls13_write_server_certificate( ssl );
+            break;
+
+        case MBEDTLS_SSL_CERTIFICATE_VERIFY:
+            ret = ssl_tls13_write_certificate_verify( ssl );
+            break;
+
         default:
             MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid state %d", ssl->state ) );
             return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );