diff --git a/mod/lesson/mod_form.php b/mod/lesson/mod_form.php
index d64cfe64f05..fa70507b258 100644
--- a/mod/lesson/mod_form.php
+++ b/mod/lesson/mod_form.php
@@ -146,15 +146,15 @@ class mod_lesson_mod_form extends moodleform_mod {
         if ($mods = get_course_mods($COURSE->id)) {
             $modinstances = array();
             foreach ($mods as $mod) {
-
-                // get the module name and then store it in a new array
+                // Get the module name and then store it in a new array.
                 if ($module = get_coursemodule_from_instance($mod->modname, $mod->instance, $COURSE->id)) {
-                    if (isset($this->_cm->id) and $this->_cm->id != $mod->id){
+                    // Exclude this lesson, if it's already been saved.
+                    if (!isset($this->_cm->id) || $this->_cm->id != $mod->id) {
                         $modinstances[$mod->id] = $mod->modname.' - '.$module->name;
                     }
                 }
             }
-            asort($modinstances); // sort by module name
+            asort($modinstances); // Sort by module name.
             $modinstances=array(0=>get_string('none'))+$modinstances;
 
             $mform->addElement('select', 'activitylink', get_string('activitylink', 'lesson'), $modinstances);