Add missing headers and fix name change issues
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index f9ba576..c00b1ac 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -1,4 +1,5 @@
 /* BEGIN_HEADER */
+#include "mbedtls/bignum.h"
 #include "mbedtls/x509_crt.h"
 #include "mbedtls/x509_csr.h"
 #include "mbedtls/pem.h"