diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index 9fb2978f38b..e84d945a2cc 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -3209,7 +3209,7 @@ function forum_post_subscription($post, $forum) {
     if ($forum->forcesubscribe == FORUM_FORCESUBSCRIBE) { // database ignored
         return "";
     } elseif (($forum->forcesubscribe == FORUM_DISALLOWSUBSCRIBE)
-        && !has_capability('moodle/course:manageactivities', $coursecontext, $USER->id)) {
+        && !has_capability('moodle/course:manageactivities', get_context_instance(CONTEXT_COURSE, $forum->course), $USER->id)) {
         if ($subscribed) {
             $action = 'unsubscribe'; // sanity check, following MDL-14558
         } else {