diff --git a/calendar/event.php b/calendar/event.php
index 04e7d7e7f15..1fb060c1120 100644
--- a/calendar/event.php
+++ b/calendar/event.php
@@ -596,8 +596,13 @@ function calendar_get_allowed_types(&$allowed) {
     $allowed->site = isteacher(SITEID);
 
     if(!empty($SESSION->cal_course_referer) && $SESSION->cal_course_referer != SITEID && isteacher($SESSION->cal_course_referer, $USER->id)) {
-        $allowed->courses = array($SESSION->cal_course_referer => 1);
-        $allowed->groups = get_groups($SESSION->cal_course_referer);
+        $course = get_record('course', 'id', $SESSION->cal_course_referer);
+
+        $allowed->courses = array($course->id => 1);
+
+        if($course->groupmode != NOGROUPS || !$course->groupmodeforce) {
+            $allowed->groups = get_groups($SESSION->cal_course_referer);
+        }
     }
 }
 
diff --git a/calendar/lib.php b/calendar/lib.php
index 93c04f3a491..1610b449606 100644
--- a/calendar/lib.php
+++ b/calendar/lib.php
@@ -642,7 +642,7 @@ function calendar_filter_controls($type, $vars = NULL, $course = NULL) {
             } else {
                 $getvars = '&from=course';
             }
-            if (isset($course->groupmode) and !$course->groupmode and $course->groupmodeforce) {
+            if (isset($course->groupmode) and $course->groupmode == NOGROUPS and $course->groupmodeforce) {
                 $groupevents = false;
             }
         break;
@@ -1055,11 +1055,11 @@ function calendar_set_filters(&$courses, &$group, &$user, $courseeventsfrom = NU
 
                     // The first time we get in here, retrieve all groupmodes at once
                     if($groupmodes === NULL) {
-                        $groupmodes = get_records_list('course', 'id', implode(',', $groupcourses), '', 'id, groupmode');
+                        $groupmodes = get_records_list('course', 'id', implode(',', $groupcourses), '', 'id, groupmode, groupmodeforce');
                     }
 
                     // If this course has groups, show events from all of them
-                    if(isset($groupmodes[$courseid]) && $groupmodes[$courseid]->groupmode != NOGROUPS && ($grouprecords = get_groups($courseid)) !== false) {
+                    if(isset($groupmodes[$courseid]) && ($groupmodes[$courseid]->groupmode != NOGROUPS || !$groupmodes[$courseid]->groupmodeforce) && ($grouprecords = get_groups($courseid)) !== false) {
                         $grouparray = array_merge($grouparray, array_keys($grouprecords));
                     }
                 }