... This function is special to all dynamic loadable modules. Take a look at the creation via the ZEND_GET_MODULE macro first: . if COMPILE_DL_FIRSTMOD ZEND_GET_MODULE(firstmod) #endif The function implementation is surrounded by a conditional compilation statement. This is needed since the function get_module() is only required if your module is built as a dynamic extension. ... Declaration of the Zend Module Block . ... Implementation of All Exported Functions ...