diff --git a/src/_cffi_src/openssl/x509.py b/src/_cffi_src/openssl/x509.py
index e7619dd..394c37c 100644
--- a/src/_cffi_src/openssl/x509.py
+++ b/src/_cffi_src/openssl/x509.py
@@ -83,6 +83,7 @@
 void X509_free(X509 *);
 X509 *X509_dup(X509 *);
 int X509_cmp(const X509 *, const X509 *);
+int X509_up_ref(X509 *);
 
 int X509_print_ex(BIO *, X509 *, unsigned long, unsigned long);
 
@@ -382,6 +383,10 @@
    opaquing. */
 #if CRYPTOGRAPHY_OPENSSL_LESS_THAN_110
 
+int X509_up_ref(X509 *x) {
+   return CRYPTO_add(&x->references, 1, CRYPTO_LOCK_X509);
+}
+
 const X509_ALGOR *X509_get0_tbs_sigalg(const X509 *x)
 {
     return x->cert_info->signature;