diff --git a/mod/book/lib.php b/mod/book/lib.php
index 4c3cde3eb2d..b6307f73f87 100644
--- a/mod/book/lib.php
+++ b/mod/book/lib.php
@@ -166,6 +166,15 @@ function book_print_recent_activity($course, $viewfullnames, $timestart) {
     return false;  //  True if anything was printed, otherwise false
 }
 
+/**
+ * This function is used by the reset_course_userdata function in moodlelib.
+ * @param $data the data submitted from the reset course.
+ * @return array status array
+ */
+function book_reset_userdata($data) {
+    return array();
+}
+
 /**
  * No cron in book.
  *