diff --git a/mod/wiki/lib.php b/mod/wiki/lib.php
index c4eee0697cc..cb31d3e673f 100644
--- a/mod/wiki/lib.php
+++ b/mod/wiki/lib.php
@@ -807,6 +807,11 @@ function mod_wiki_core_calendar_provide_event_action(calendar_event $event,
                                                     \core_calendar\action_factory $factory) {
     $cm = get_fast_modinfo($event->courseid)->instances['wiki'][$event->instance];
 
+    if (!$cm->uservisible) {
+        // The module is not visible to the user for any reason.
+        return null;
+    }
+
     $completion = new \completion_info($cm->get_course());
 
     $completiondata = $completion->get_data($cm, false);
diff --git a/mod/wiki/tests/lib_test.php b/mod/wiki/tests/lib_test.php
index 9ecaf09a7a2..3f1e989cc00 100644
--- a/mod/wiki/tests/lib_test.php
+++ b/mod/wiki/tests/lib_test.php
@@ -765,6 +765,34 @@ class mod_wiki_lib_testcase extends advanced_testcase {
         $this->assertTrue($actionevent->is_actionable());
     }
 
+    public function test_wiki_core_calendar_provide_event_action_for_non_user() {
+        global $CFG;
+
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        // Create the activity.
+        $course = $this->getDataGenerator()->create_course();
+        $wiki = $this->getDataGenerator()->create_module('wiki', array('course' => $course->id));
+
+        // Create a calendar event.
+        $event = $this->create_action_event($course->id, $wiki->id,
+                \core_completion\api::COMPLETION_EVENT_TYPE_DATE_COMPLETION_EXPECTED);
+
+        // Now, log out.
+        $CFG->forcelogin = true; // We don't want to be logged in as guest, as guest users might still have some capabilities.
+        $this->setUser();
+
+        // Create an action factory.
+        $factory = new \core_calendar\action_factory();
+
+        // Decorate action event for the student.
+        $actionevent = mod_wiki_core_calendar_provide_event_action($event, $factory);
+
+        // Confirm the event is not shown at all.
+        $this->assertNull($actionevent);
+    }
+
     public function test_wiki_core_calendar_provide_event_action_already_completed() {
         global $CFG;