So I decided to write an extension for php. Everything seems to be fine except I'm stuck on a tiny problem. I have php-5.4.9 source codes. There is file ext/standard/mail.c with awesome function PHPAPI int php_mail(char *to, char *subject, char *message, char *headers, char *extra_cmd TSRMLS_DC) In my extension, in acme.c I have includes ... #include "php.h" #include "ext/standard/php_mail.h" #inc