diff --git a/include/openssl/dh.h b/include/openssl/dh.h
index ed2396d..9f92a06 100644
--- a/include/openssl/dh.h
+++ b/include/openssl/dh.h
@@ -210,7 +210,7 @@
 
 OPENSSL_EXPORT int DH_get_ex_new_index(long argl, void *argp,
                                        CRYPTO_EX_unused *unused,
-                                       CRYPTO_EX_dup *dup_func,
+                                       CRYPTO_EX_dup *dup_unused,
                                        CRYPTO_EX_free *free_func);
 OPENSSL_EXPORT int DH_set_ex_data(DH *d, int idx, void *arg);
 OPENSSL_EXPORT void *DH_get_ex_data(DH *d, int idx);
diff --git a/include/openssl/dsa.h b/include/openssl/dsa.h
index 2988877..afe0291 100644
--- a/include/openssl/dsa.h
+++ b/include/openssl/dsa.h
@@ -296,7 +296,7 @@
 
 OPENSSL_EXPORT int DSA_get_ex_new_index(long argl, void *argp,
                                         CRYPTO_EX_unused *unused,
-                                        CRYPTO_EX_dup *dup_func,
+                                        CRYPTO_EX_dup *dup_unused,
                                         CRYPTO_EX_free *free_func);
 OPENSSL_EXPORT int DSA_set_ex_data(DSA *d, int idx, void *arg);
 OPENSSL_EXPORT void *DSA_get_ex_data(const DSA *d, int idx);
diff --git a/include/openssl/ec_key.h b/include/openssl/ec_key.h
index 2186f02..3aeaa78 100644
--- a/include/openssl/ec_key.h
+++ b/include/openssl/ec_key.h
@@ -223,7 +223,7 @@
 
 OPENSSL_EXPORT int EC_KEY_get_ex_new_index(long argl, void *argp,
                                            CRYPTO_EX_unused *unused,
-                                           CRYPTO_EX_dup *dup_func,
+                                           CRYPTO_EX_dup *dup_unused,
                                            CRYPTO_EX_free *free_func);
 OPENSSL_EXPORT int EC_KEY_set_ex_data(EC_KEY *r, int idx, void *arg);
 OPENSSL_EXPORT void *EC_KEY_get_ex_data(const EC_KEY *r, int idx);
diff --git a/include/openssl/ex_data.h b/include/openssl/ex_data.h
index e78e070..5d1a45c 100644
--- a/include/openssl/ex_data.h
+++ b/include/openssl/ex_data.h
@@ -134,16 +134,14 @@
 
 #if 0 /* Sample */
 
-/* TYPE_get_ex_new_index allocates a new index for |TYPE|. See the
- * descriptions of the callback typedefs for details of when they are
- * called. Any of the callback arguments may be NULL. The |argl| and |argp|
- * arguments are opaque values that are passed to the callbacks. It returns the
- * new index or a negative number on error.
- *
- * TODO(fork): this should follow the standard calling convention. */
+/* TYPE_get_ex_new_index allocates a new index for |TYPE|. An optional
+ * |free_func| argument may be provided which is called when the owning object
+ * is destroyed. See |CRYPTO_EX_free| for details. The |argl| and |argp|
+ * arguments are opaque values that are passed to the callback. It returns the
+ * new index or a negative number on error. */
 OPENSSL_EXPORT int TYPE_get_ex_new_index(long argl, void *argp,
                                          CRYPTO_EX_unused *unused,
-                                         CRYPTO_EX_dup *dup_func,
+                                         CRYPTO_EX_dup *dup_unused,
                                          CRYPTO_EX_free *free_func);
 
 /* TYPE_set_ex_data sets an extra data pointer on |t|. The |index| argument
@@ -176,24 +174,16 @@
 typedef void CRYPTO_EX_free(void *parent, void *ptr, CRYPTO_EX_DATA *ad,
                             int index, long argl, void *argp);
 
-/* CRYPTO_EX_dup is a callback function that is called when an object of the
- * class is being copied and thus the ex_data linked to it also needs to be
- * copied. On entry, |*from_d| points to the data for this index from the
- * original object. When the callback returns, |*from_d| will be set as the
- * data for this index in |to|.
- *
- * This callback may be called with a NULL value for |*from_d| if |from| has no
- * value set for this index. However, the callbacks may also be skipped entirely
- * if no extra data pointers are set on |from| at all. */
-typedef int CRYPTO_EX_dup(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
-                          void **from_d, int index, long argl, void *argp);
-
 
 /* Deprecated functions. */
 
 /* CRYPTO_cleanup_all_ex_data does nothing. */
 OPENSSL_EXPORT void CRYPTO_cleanup_all_ex_data(void);
 
+/* CRYPTO_EX_dup is a legacy callback function type which is ignored. */
+typedef int CRYPTO_EX_dup(CRYPTO_EX_DATA *to, const CRYPTO_EX_DATA *from,
+                          void **from_d, int index, long argl, void *argp);
+
 
 /* Private structures. */
 
diff --git a/include/openssl/rsa.h b/include/openssl/rsa.h
index c4d7f53..caf4a42 100644
--- a/include/openssl/rsa.h
+++ b/include/openssl/rsa.h
@@ -454,7 +454,7 @@
 
 OPENSSL_EXPORT int RSA_get_ex_new_index(long argl, void *argp,
                                         CRYPTO_EX_unused *unused,
-                                        CRYPTO_EX_dup *dup_func,
+                                        CRYPTO_EX_dup *dup_unused,
                                         CRYPTO_EX_free *free_func);
 OPENSSL_EXPORT int RSA_set_ex_data(RSA *r, int idx, void *arg);
 OPENSSL_EXPORT void *RSA_get_ex_data(const RSA *r, int idx);
diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index 581da2a..55e53da 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -2913,7 +2913,7 @@
 OPENSSL_EXPORT void *SSL_get_ex_data(const SSL *ssl, int idx);
 OPENSSL_EXPORT int SSL_get_ex_new_index(long argl, void *argp,
                                         CRYPTO_EX_unused *unused,
-                                        CRYPTO_EX_dup *dup_func,
+                                        CRYPTO_EX_dup *dup_unused,
                                         CRYPTO_EX_free *free_func);
 
 OPENSSL_EXPORT int SSL_SESSION_set_ex_data(SSL_SESSION *session, int idx,
@@ -2922,14 +2922,14 @@
                                              int idx);
 OPENSSL_EXPORT int SSL_SESSION_get_ex_new_index(long argl, void *argp,
                                                 CRYPTO_EX_unused *unused,
-                                                CRYPTO_EX_dup *dup_func,
+                                                CRYPTO_EX_dup *dup_unused,
                                                 CRYPTO_EX_free *free_func);
 
 OPENSSL_EXPORT int SSL_CTX_set_ex_data(SSL_CTX *ctx, int idx, void *data);
 OPENSSL_EXPORT void *SSL_CTX_get_ex_data(const SSL_CTX *ctx, int idx);
 OPENSSL_EXPORT int SSL_CTX_get_ex_new_index(long argl, void *argp,
                                             CRYPTO_EX_unused *unused,
-                                            CRYPTO_EX_dup *dup_func,
+                                            CRYPTO_EX_dup *dup_unused,
                                             CRYPTO_EX_free *free_func);
 
 
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);
diff --git a/include/openssl/x509_vfy.h b/include/openssl/x509_vfy.h
index 90a9dd6..85aa1f9 100644
--- a/include/openssl/x509_vfy.h
+++ b/include/openssl/x509_vfy.h
@@ -513,7 +513,7 @@
 #endif
 
 OPENSSL_EXPORT int X509_STORE_CTX_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_STORE_CTX_set_ex_data(X509_STORE_CTX *ctx,int idx,void *data);
 OPENSSL_EXPORT void *	X509_STORE_CTX_get_ex_data(X509_STORE_CTX *ctx,int idx);
 OPENSSL_EXPORT int	X509_STORE_CTX_get_error(X509_STORE_CTX *ctx);