diff --git a/sites/all/modules/contrib/activitystream/activitystream.module b/sites/all/modules/contrib/activitystream/activitystream.module
index 2453209..cafbe5d 100644
--- a/sites/all/modules/contrib/activitystream/activitystream.module
+++ b/sites/all/modules/contrib/activitystream/activitystream.module
@@ -490,7 +490,11 @@ function activitystream_cron() {
   module_load_include('inc', 'node', 'node.pages');
   $number_of_hours = variable_get('activitystream_cron_hours', 1);
   $active_days = variable_get('activitystream_active_days', 30);
-  $result = db_query('SELECT a.uid, a.userid, a.password, a.feed, a.module FROM {activitystream_accounts} a LEFT JOIN {users} u on a.uid = u.uid  WHERE a.lastfetch < date_sub(now( ) , INTERVAL %d HOUR) AND u.access > unix_timestamp(date_sub(now( ) , INTERVAL %d day)) ORDER BY a.lastfetch DESC, u.access DESC', $number_of_hours, $active_days);
+
+  // calculate timestamps in php to avoid MySQL specific functions
+  $hours_ago = date('Y-m-d H:i:s', time() - ($number_of_hours * 60 * 60));
+  $days_ago = time() - ($active_days * 24 * 60 * 60);
+  $result = db_query('SELECT a.uid, a.userid, a.password, a.feed, a.module FROM {activitystream_accounts} a LEFT JOIN {users} u on a.uid = u.uid  WHERE a.lastfetch < \'%s\' AND u.access > %d ORDER BY a.lastfetch DESC, u.access DESC', $hours_ago, $days_ago);
   $users = array();
   while ($user = db_fetch_object($result)) {
     $users[] = $user;