diff --git a/include/mbedtls/ssl.h b/include/mbedtls/ssl.h
index b8215a4..bbe9a83 100644
--- a/include/mbedtls/ssl.h
+++ b/include/mbedtls/ssl.h
@@ -1090,6 +1090,12 @@
     unsigned badmac_seen;       /*!< records with a bad MAC received    */
 #endif /* MBEDTLS_SSL_DTLS_BADMAC_LIMIT */
 
+#if defined(MBEDTLS_X509_CRT_PARSE_C)
+    /** Callback to customize X.509 certificate chain verification          */
+    int (*f_vrfy)(void *, mbedtls_x509_crt *, int, uint32_t *);
+    void *p_vrfy;                   /*!< context for X.509 verify calllback */
+#endif
+
     mbedtls_ssl_send_t *f_send; /*!< Callback for network send */
     mbedtls_ssl_recv_t *f_recv; /*!< Callback for network receive */
     mbedtls_ssl_recv_timeout_t *f_recv_timeout;