diff --git a/calendar/lib.php b/calendar/lib.php
index f854ece5103..0ce9f1b5d54 100644
--- a/calendar/lib.php
+++ b/calendar/lib.php
@@ -737,12 +737,12 @@ function calendar_get_events($tstart, $tend, $users, $groups, $courses, $withdur
         // Events from a number of users
         if(!empty($whereclause)) $whereclause .= ' OR';
         list($insqlusers, $inparamsusers) = $DB->get_in_or_equal($users, SQL_PARAMS_NAMED);
-        $whereclause .= " (userid $insqlusers AND courseid = 0 AND groupid = 0)";
+        $whereclause .= " (e.userid $insqlusers AND e.courseid = 0 AND e.groupid = 0)";
         $params = array_merge($params, $inparamsusers);
     } else if($users === true) {
         // Events from ALL users
         if(!empty($whereclause)) $whereclause .= ' OR';
-        $whereclause .= ' (userid != 0 AND courseid = 0 AND groupid = 0)';
+        $whereclause .= ' (e.userid != 0 AND e.courseid = 0 AND e.groupid = 0)';
     } else if($users === false) {
         // No user at all, do nothing
     }
@@ -751,24 +751,24 @@ function calendar_get_events($tstart, $tend, $users, $groups, $courses, $withdur
         // Events from a number of groups
         if(!empty($whereclause)) $whereclause .= ' OR';
         list($insqlgroups, $inparamsgroups) = $DB->get_in_or_equal($groups, SQL_PARAMS_NAMED);
-        $whereclause .= " groupid $insqlgroups ";
+        $whereclause .= " e.groupid $insqlgroups ";
         $params = array_merge($params, $inparamsgroups);
     } else if($groups === true) {
         // Events from ALL groups
         if(!empty($whereclause)) $whereclause .= ' OR ';
-        $whereclause .= ' groupid != 0';
+        $whereclause .= ' e.groupid != 0';
     }
     // boolean false (no groups at all): we don't need to do anything
 
     if ((is_array($courses) && !empty($courses)) or is_numeric($courses)) {
         if(!empty($whereclause)) $whereclause .= ' OR';
         list($insqlcourses, $inparamscourses) = $DB->get_in_or_equal($courses, SQL_PARAMS_NAMED);
-        $whereclause .= " (groupid = 0 AND courseid $insqlcourses)";
+        $whereclause .= " (e.groupid = 0 AND e.courseid $insqlcourses)";
         $params = array_merge($params, $inparamscourses);
     } else if ($courses === true) {
         // Events from ALL courses
         if(!empty($whereclause)) $whereclause .= ' OR';
-        $whereclause .= ' (groupid = 0 AND courseid != 0)';
+        $whereclause .= ' (e.groupid = 0 AND e.courseid != 0)';
     }
 
     // Security check: if, by now, we have NOTHING in $whereclause, then it means
@@ -780,10 +780,10 @@ function calendar_get_events($tstart, $tend, $users, $groups, $courses, $withdur
     }
 
     if($withduration) {
-        $timeclause = '(timestart >= '.$tstart.' OR timestart + timeduration > '.$tstart.') AND timestart <= '.$tend;
+        $timeclause = '(e.timestart >= '.$tstart.' OR e.timestart + e.timeduration > '.$tstart.') AND e.timestart <= '.$tend;
     }
     else {
-        $timeclause = 'timestart >= '.$tstart.' AND timestart <= '.$tend;
+        $timeclause = 'e.timestart >= '.$tstart.' AND e.timestart <= '.$tend;
     }
     if(!empty($whereclause)) {
         // We have additional constraints
@@ -795,10 +795,17 @@ function calendar_get_events($tstart, $tend, $users, $groups, $courses, $withdur
     }
 
     if ($ignorehidden) {
-        $whereclause .= ' AND visible = 1';
+        $whereclause .= ' AND e.visible = 1';
     }
 
-    $events = $DB->get_records_select('event', $whereclause, $params, 'timestart');
+    $sql = "SELECT e.*
+              FROM {event} e
+         LEFT JOIN {modules} m ON e.modulename = m.name
+                -- Non visible modules will have a value of 0.
+             WHERE (m.visible = 1 OR m.visible IS NULL) AND $whereclause
+          ORDER BY e.timestart";
+    $events = $DB->get_records_sql($sql, $params);
+
     if ($events === false) {
         $events = array();
     }