diff --git a/programs/x509/cert_app.c b/programs/x509/cert_app.c
index 84f67e6..3f50a7a 100644
--- a/programs/x509/cert_app.c
+++ b/programs/x509/cert_app.c
@@ -29,6 +29,9 @@
 #include "mbedtls/platform.h"
 #else
 #include <stdio.h>
+#include <stdlib.h>
+#define mbedtls_time       time
+#define mbedtls_time_t     time_t
 #define mbedtls_fprintf    fprintf
 #define mbedtls_printf     printf
 #endif