diff --git a/include/openssl/x509.h b/include/openssl/x509.h
index 52e5df0..f416045 100644
--- a/include/openssl/x509.h
+++ b/include/openssl/x509.h
@@ -779,7 +779,7 @@
 OPENSSL_EXPORT int X509_up_ref(X509 *x);
 
 OPENSSL_EXPORT int X509_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,
-	     CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func);
+	     CRYPTO_EX_dup *dup_unused, CRYPTO_EX_free *free_func);
 OPENSSL_EXPORT int X509_set_ex_data(X509 *r, int idx, void *arg);
 OPENSSL_EXPORT void *X509_get_ex_data(X509 *r, int idx);
 OPENSSL_EXPORT int		i2d_X509_AUX(X509 *a,unsigned char **pp);