diff --git a/cohort/edit_form.php b/cohort/edit_form.php
index fe3ce492461..957607171c8 100644
--- a/cohort/edit_form.php
+++ b/cohort/edit_form.php
@@ -98,7 +98,7 @@ class cohort_edit_form extends moodleform {
             $options[$syscontext->id] = print_context_name($syscontext);
         }
         foreach ($displaylist as $cid=>$name) {
-            $context = context_coursecat::instance($cid, MUST_EXIST);
+            $context = context_coursecat::instance($cid);
             $options[$context->id] = $name;
         }
         // always add current - this is not likely, but if the logic gets changed it might be a problem
diff --git a/cohort/lib.php b/cohort/lib.php
index ce512729766..223644b52e6 100644
--- a/cohort/lib.php
+++ b/cohort/lib.php
@@ -110,10 +110,10 @@ function cohort_delete_category($category) {
     global $DB;
     // TODO: make sure that cohorts are really, really not used anywhere and delete, for now just move to parent or system context
 
-    $oldcontext = context_coursecat::instance($category->id, MUST_EXIST);
+    $oldcontext = context_coursecat::instance($category->id);
 
     if ($category->parent and $parent = $DB->get_record('course_categories', array('id'=>$category->parent))) {
-        $parentcontext = context_coursecat::instance($parent->id, MUST_EXIST);
+        $parentcontext = context_coursecat::instance($parent->id);
         $sql = "UPDATE {cohort} SET contextid = :newcontext WHERE contextid = :oldcontext";
         $params = array('oldcontext'=>$oldcontext->id, 'newcontext'=>$parentcontext->id);
     } else {
@@ -165,7 +165,7 @@ function cohort_remove_member($cohortid, $userid) {
 function cohort_get_visible_list($course) {
     global $DB, $USER;
 
-    $context = context_course::instance($course->id, MUST_EXIST);
+    $context = context_course::instance($course->id);
     list($esql, $params) = get_enrolled_sql($context);
     $parentsql = get_related_contexts_string($context);