PHP_HTTP_API void php_http_message_update_headers(php_http_message_t *msg);
-PHP_HTTP_API zval *php_http_message_header(php_http_message_t *msg, char *key_str, size_t key_len, int join);
+PHP_HTTP_API zval *php_http_message_header(php_http_message_t *msg, const char *key_str, size_t key_len, int join);
PHP_HTTP_API zend_bool php_http_message_is_multipart(php_http_message_t *msg, char **boundary);
PHP_HTTP_API void php_http_message_to_string(php_http_message_t *msg, char **string, size_t *length);