diff --git a/includes/rapidill.inc b/includes/rapidill.inc
index f50c5e2..9a72f6d 100644
--- a/includes/rapidill.inc
+++ b/includes/rapidill.inc
@@ -18,7 +18,7 @@ use RapidIll\RequestType;
  *
  * Usage (from the form submit handler):
  * @code
- *   module_load_include('inc', 'upei_roblib_ill', 'includes/rapidill');
+ *   \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/rapidill');
  *   $handler = new RapidIllRequestHandler();
  *   $response = $handler->submitRequest($form_state);
  * @endcode
@@ -214,8 +214,8 @@ class RapidIllRequestHandler {
    *   optionally a 'RequestNumber' key on success.
    */
   public function submitRequest(FormStateInterface $form_state): array {
-    module_load_include('inc', 'upei_roblib_ill', 'includes/db');
-    module_load_include('inc', 'upei_roblib_ill', 'includes/utilities');
+    \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/db');
+    \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/utilities');
 
     // Build the Relais-style array for logging purposes.
     $relais_arr = upei_roblib_ill_build_relais_arr($form_state);
diff --git a/includes/relais.inc b/includes/relais.inc
index cdd79e8..df6bab4 100644
--- a/includes/relais.inc
+++ b/includes/relais.inc
@@ -29,8 +29,8 @@ function upei_roblib_ill_get_pub_type($genre) {
  * @return array|mixed
  */
 function upei_roblib_ill_add_request($form_state, $aid) {
-  module_load_include('inc', 'upei_roblib_ill', 'includes/db');
-  module_load_include('inc', 'upei_roblib_ill', 'includes/utilities');
+  \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/db');
+  \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/utilities');
   $config = \Drupal::config('upei_roblib_ill.settings');
   $url = trim($config->get('ill_add_url'));
   $relais_arr = upei_roblib_ill_build_relais_arr($form_state);
@@ -69,7 +69,7 @@ function upei_roblib_ill_add_request($form_state, $aid) {
  * @return array
  */
 function upei_roblib_ill_build_relais_arr($form_state) {
-  module_load_include('inc', 'upei_roblib_ill', 'includes/utilities');
+  \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/utilities');
   $storage = $form_state->getStorage();
   $ill_request = $storage['request'];
   $values = $form_state->getValues();
diff --git a/src/Form/RoblibIllLoanForm.php b/src/Form/RoblibIllLoanForm.php
index dc876c0..86f20f3 100644
--- a/src/Form/RoblibIllLoanForm.php
+++ b/src/Form/RoblibIllLoanForm.php
@@ -33,7 +33,7 @@ class RoblibIllLoanForm extends FormBase {
    * {@inheritdoc}
    */
   public function validateForm(array &$form, FormStateInterface $form_state) {
-    module_load_include('inc', 'upei_roblib_ill', 'includes/relais');
+    \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/relais');
     $values = $form_state->getValues();
     if ($form_state->get('step') == 2) {
       $is_valid_email = \Drupal::service('email.validator')->isValid($values['DeliveryAddress']);
@@ -54,7 +54,7 @@ class RoblibIllLoanForm extends FormBase {
         $form_state->setErrorByName('Surname', $aid['Problem']['Message']);
         // Log invalid requests, we need to build the full array here to log it, even though we won't send it yet as auth has failed.
         //$form_state->set('upei_roblib_ill_auth_form_storage') = $form_state->getValues();
-        module_load_include('inc', 'upei_roblib_ill', 'includes/db');
+        \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/db');
         $arr = upei_roblib_ill_build_relais_arr($form_state);
         upei_roblib_ill_log_request($arr, $aid);
       }
@@ -127,7 +127,7 @@ class RoblibIllLoanForm extends FormBase {
   }
 
   public function doiCallback(array &$form, FormStateInterface $form_state) {
-    module_load_include('inc', 'upei_roblib_ill', 'includes/doi');
+    \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/doi');
     $doi = $form_state->getValue('doi');
     $form = upei_roblib_ill_doi_get_data($form, $doi);
     return $form;
@@ -145,7 +145,7 @@ class RoblibIllLoanForm extends FormBase {
    *   An array representing the bibliographic form.
    */
   function ill_request_form($form, &$form_state) {
-    module_load_include('inc', 'upei_roblib_ill', 'includes/utilities');
+    \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/utilities');
     $config = \Drupal::config('upei_roblib_ill.settings');
     $form['#prefix'] = '<div id="upei-roblib-ill-request-form">';
     $form['#suffix'] = '<div class="roblib-required">* = Required Field</div></div>';
@@ -359,7 +359,7 @@ class RoblibIllLoanForm extends FormBase {
    *   An array representing the bibliographic form.
    */
   function ill_auth_form($form, &$form_state) {
-    module_load_include('inc', 'upei_roblib_ill', 'includes/utilities');
+    \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/utilities');
     $form['#prefix'] = upei_roblib_format_biblio_info($form_state);
     $form['#suffix'] = '<div class="roblib-required">* = Required Field</div>
 <div class="roblib-FOIPP"><strong>Protection of Privacy</strong> - The personal information requested
diff --git a/upei_roblib_ill.module b/upei_roblib_ill.module
index 08c69ae..1d198ec 100644
--- a/upei_roblib_ill.module
+++ b/upei_roblib_ill.module
@@ -9,7 +9,7 @@
  * @return array
  */
 function upei_roblib_ill_doi_callback($form, &$form_state) {
-  module_load_include('inc', 'upei_roblib_ill', 'includes/doi');
+  \Drupal::moduleHandler()->loadInclude('upei_roblib_ill', 'inc', 'includes/doi');
   $form = upei_roblib_ill_doi_get_data($form, $form_state['values']['doi']);
   return $form;
 }