diff --git a/include/openssl/ssl.h b/include/openssl/ssl.h
index d629b8f..8454c30 100644
--- a/include/openssl/ssl.h
+++ b/include/openssl/ssl.h
@@ -565,19 +565,25 @@
 #define TLS1_3_DRAFT_VERSION 14
 
 /* SSL_CTX_set_min_proto_version sets the minimum protocol version for |ctx| to
- * |version|. It returns one on success and zero if |version| is invalid. */
-OPENSSL_EXPORT int SSL_CTX_set_min_proto_version(SSL_CTX *ctx, uint16_t version);
+ * |version|. If |version| is zero, the default minimum version is used. It
+ * returns one on success and zero if |version| is invalid. */
+OPENSSL_EXPORT int SSL_CTX_set_min_proto_version(SSL_CTX *ctx,
+                                                 uint16_t version);
 
 /* SSL_CTX_set_max_proto_version sets the maximum protocol version for |ctx| to
- * |version|. It returns one on success and zero if |version| is invalid. */
-OPENSSL_EXPORT int SSL_CTX_set_max_proto_version(SSL_CTX *ctx, uint16_t version);
+ * |version|. If |version| is zero, the default maximum version is used. It
+ * returns one on success and zero if |version| is invalid. */
+OPENSSL_EXPORT int SSL_CTX_set_max_proto_version(SSL_CTX *ctx,
+                                                 uint16_t version);
 
 /* SSL_set_min_proto_version sets the minimum protocol version for |ssl| to
- * |version|. It returns one on success and zero if |version| is invalid. */
+ * |version|. If |version| is zero, the default minimum version is used. It
+ * returns one on success and zero if |version| is invalid. */
 OPENSSL_EXPORT int SSL_set_min_proto_version(SSL *ssl, uint16_t version);
 
 /* SSL_set_max_proto_version sets the maximum protocol version for |ssl| to
- * |version|. It returns one on success and zero if |version| is invalid. */
+ * |version|. If |version| is zero, the default maximum version is used. It
+ * returns one on success and zero if |version| is invalid. */
 OPENSSL_EXPORT int SSL_set_max_proto_version(SSL *ssl, uint16_t version);
 
 /* SSL_version returns the TLS or DTLS protocol version used by |ssl|, which is