diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index 5d68e16..24094ec 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -397,7 +397,7 @@
                                         serial_arg->len) == 0);
     TEST_ASSERT(mbedtls_x509write_crt_set_serial(&crt, &serial_mpi) == 0);
 #else
-    TEST_ASSERT(mbedtls_x509write_crt_set_serial_new(&crt, serial_arg->x,
+    TEST_ASSERT(mbedtls_x509write_crt_set_serial_raw(&crt, serial_arg->x,
                                                      serial_arg->len) == 0);
 #endif
     TEST_ASSERT(mbedtls_x509write_crt_set_validity(&crt, not_before,
@@ -587,7 +587,7 @@
     mbedtls_mpi_free(&serial_mpi);
 #endif
 
-    TEST_EQUAL(mbedtls_x509write_crt_set_serial_new(&ctx, invalid_serial,
+    TEST_EQUAL(mbedtls_x509write_crt_set_serial_raw(&ctx, invalid_serial,
                                                     sizeof(invalid_serial)),
                MBEDTLS_ERR_X509_BAD_INPUT_DATA);