diff --git a/lib/navigationlib.php b/lib/navigationlib.php
index d858fb2dad4..1af75d29eb9 100644
--- a/lib/navigationlib.php
+++ b/lib/navigationlib.php
@@ -1487,9 +1487,10 @@ class global_navigation extends navigation_node {
      * @return bool
      */
     protected function show_my_categories() {
-        global $CFG, $DB;
+        global $CFG;
         if ($this->showmycategories === null) {
-            $this->showmycategories = !empty($CFG->navshowmycoursecategories) && $DB->count_records('course_categories') > 1;
+            require_once('coursecatlib.php');
+            $this->showmycategories = !empty($CFG->navshowmycoursecategories) && coursecat::count_all() > 1;
         }
         return $this->showmycategories;
     }
@@ -2881,7 +2882,7 @@ class global_navigation extends navigation_node {
      * They've expanded the 'my courses' branch.
      */
     protected function load_courses_enrolled() {
-        global $CFG, $DB;
+        global $CFG;
         $sortorder = 'visible DESC';
         // Prevent undefined $CFG->navsortmycoursessort errors.
         if (empty($CFG->navsortmycoursessort)) {
@@ -2891,35 +2892,61 @@ class global_navigation extends navigation_node {
         $sortorder = $sortorder . ',' . $CFG->navsortmycoursessort . ' ASC';
         $courses = enrol_get_my_courses(null, $sortorder);
         if (count($courses) && $this->show_my_categories()) {
-            // OK Actually we are loading categories. We only want to load categories that have a parent of 0.
-            // In order to make sure we load everything required we must first find the categories that are not
-            // base categories and work out the bottom category in thier path.
+            // Generate an array containing unique values of all the courses' categories.
             $categoryids = array();
             foreach ($courses as $course) {
+                if (in_array($course->category, $categoryids)) {
+                    continue;
+                }
                 $categoryids[] = $course->category;
             }
-            $categoryids = array_unique($categoryids);
-            list($sql, $params) = $DB->get_in_or_equal($categoryids);
-            $categories = $DB->get_recordset_select('course_categories', 'id '.$sql.' AND parent <> 0', $params, 'sortorder, id', 'id, path');
-            foreach ($categories as $category) {
-                $bits = explode('/', trim($category->path,'/'));
-                $categoryids[] = array_shift($bits);
-            }
-            $categoryids = array_unique($categoryids);
-            $categories->close();
 
-            // Now we load the base categories.
-            list($sql, $params) = $DB->get_in_or_equal($categoryids);
-            $categories = $DB->get_recordset_select('course_categories', 'id '.$sql.' AND parent = 0', $params, 'sortorder, id');
-            foreach ($categories as $category) {
-                $this->add_category($category, $this->rootnodes['mycourses'], self::TYPE_MY_CATEGORY);
+            // Array of category IDs that include the categories of the user's courses and the related course categories.
+            $fullpathcategoryids = [];
+            // Get the course categories for the enrolled courses' category IDs.
+            require_once('coursecatlib.php');
+            $mycoursecategories = coursecat::get_many($categoryids);
+            // Loop over each of these categories and build the category tree using each category's path.
+            foreach ($mycoursecategories as $mycoursecat) {
+                $pathcategoryids = explode('/', $mycoursecat->path);
+                // First element of the exploded path is empty since paths begin with '/'.
+                array_shift($pathcategoryids);
+                // Merge the exploded category IDs into the full list of category IDs that we will fetch.
+                $fullpathcategoryids = array_merge($fullpathcategoryids, $pathcategoryids);
             }
-            $categories->close();
-        } else {
-            foreach ($courses as $course) {
-                $this->add_course($course, false, self::COURSE_MY);
+
+            // Fetch all of the categories related to the user's courses.
+            $pathcategories = coursecat::get_many($fullpathcategoryids);
+            // Loop over each of these categories and build the category tree.
+            foreach ($pathcategories as $coursecat) {
+                // No need to process categories that have already been added.
+                if (isset($this->addedcategories[$coursecat->id])) {
+                    continue;
+                }
+
+                // Get this course category's parent node.
+                $parent = null;
+                if ($coursecat->parent && isset($this->addedcategories[$coursecat->parent])) {
+                    $parent = $this->addedcategories[$coursecat->parent];
+                }
+                if (!$parent) {
+                    // If it has no parent, then it should be right under the My courses node.
+                    $parent = $this->rootnodes['mycourses'];
+                }
+
+                // Build the category object based from the coursecat object.
+                $mycategory = new stdClass();
+                $mycategory->id = $coursecat->id;
+                $mycategory->name = $coursecat->name;
+                $mycategory->visible = $coursecat->visible;
+
+                // Add this category to the nav tree.
+                $this->add_category($mycategory, $parent, self::TYPE_MY_CATEGORY);
             }
         }
+        foreach ($courses as $course) {
+            $this->add_course($course, false, self::COURSE_MY);
+        }
     }
 }