diff --git a/ext/date/php_date.h b/ext/date/php_date.h
index 7f46693466c..d599e8fb37e 100644
--- a/ext/date/php_date.h
+++ b/ext/date/php_date.h
@@ -198,6 +198,7 @@ PHPAPI timelib_tzinfo *get_timezone_info(TSRMLS_D);
 
 /* Grabbing CE's so that other exts can use the date objects too */
 PHPAPI zend_class_entry *php_date_get_date_ce(void);
+PHPAPI zend_class_entry *php_date_get_immutable_ce(void);
 PHPAPI zend_class_entry *php_date_get_timezone_ce(void);
 
 /* Functions for creating DateTime objects, and initializing them from a string */