diff --git a/modules/demo/tmgmt_demo.info.yml b/modules/demo/tmgmt_demo.info.yml
index c94e727..f60eb39 100644
--- a/modules/demo/tmgmt_demo.info.yml
+++ b/modules/demo/tmgmt_demo.info.yml
@@ -3,7 +3,7 @@ type: module
 description: All elements for a functioning demo.
 package: Translation Management
 core: 8.x
-hidden: FALSE
+hidden: false
 
 dependencies:
  - tmgmt
diff --git a/sources/tmgmt_config/src/ConfigSourcePluginUi.php b/sources/tmgmt_config/src/ConfigSourcePluginUi.php
index 7dca1d1..9d25e9b 100644
--- a/sources/tmgmt_config/src/ConfigSourcePluginUi.php
+++ b/sources/tmgmt_config/src/ConfigSourcePluginUi.php
@@ -225,7 +225,7 @@ class ConfigSourcePluginUi extends SourcePluginUiBase {
    *   Configuration name.
    *
    * @return bool
-   *   Returns true, if it is translatable.
+   *   Returns TRUE, if it is translatable.
    */
   public function isTranslated($langcode, $name) {
     $config = \Drupal::languageManager()->getLanguageConfigOverride($langcode, $name);
diff --git a/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php b/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php
index dd390d7..e584478 100644
--- a/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php
+++ b/sources/tmgmt_config/src/Plugin/tmgmt/Source/ConfigSource.php
@@ -128,7 +128,7 @@ class ConfigSource extends SourcePluginBase implements ContainerFactoryPluginInt
       $entity_type->getConfigPrefix();
 
       $pos = strpos($job_item->getItemId(), $entity_type->getConfigPrefix());
-      if (($pos !== false)) {
+      if (($pos !== FALSE)) {
         $entity_id = str_replace($entity_type->getConfigPrefix() . '.', '', $job_item->getItemId());
       }
       else {
diff --git a/src/SourcePluginInterface.php b/src/SourcePluginInterface.php
index a4da875..5144b5e 100644
--- a/src/SourcePluginInterface.php
+++ b/src/SourcePluginInterface.php
@@ -33,7 +33,7 @@ interface SourcePluginInterface extends PluginInspectionInterface {
    * @param \Drupal\tmgmt\JobItemInterface $job_item
    *   The job item entity.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the translation was saved successfully, FALSE otherwise.
    */
   public function saveTranslation(JobItemInterface $job_item);
diff --git a/src/SourcePluginUiBase.php b/src/SourcePluginUiBase.php
index 1765b91..245048c 100644
--- a/src/SourcePluginUiBase.php
+++ b/src/SourcePluginUiBase.php
@@ -160,7 +160,7 @@ class SourcePluginUiBase extends PluginBase implements SourcePluginUiInterface {
    *   Entity type.
    *
    * @return bool
-   *   Returns true, if redirect has been set.
+   *   Returns TRUE, if redirect has been set.
    */
   public function overviewSearchFormRedirect(array $form, FormStateInterface $form_state, $type) {
     if ($form_state->getTriggeringElement()['#id'] == 'edit-search-cancel') {
diff --git a/src/TranslatorPluginInterface.php b/src/TranslatorPluginInterface.php
index c6af5ce..e607b9f 100644
--- a/src/TranslatorPluginInterface.php
+++ b/src/TranslatorPluginInterface.php
@@ -22,7 +22,7 @@ interface TranslatorPluginInterface extends PluginInspectionInterface {
    * @param TranslatorInterface $translator
    *   The translator entity.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the translator plugin is available, FALSE otherwise.
    */
   public function isAvailable(TranslatorInterface $translator);
@@ -48,7 +48,7 @@ interface TranslatorPluginInterface extends PluginInspectionInterface {
    * @param \Drupal\tmgmt\JobInterface $job
    *   The Job entity that should be translated.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the job can be processed and translated, FALSE otherwise.
    */
   public function canTranslate(TranslatorInterface $translator, JobInterface $job);
@@ -198,7 +198,7 @@ interface TranslatorPluginInterface extends PluginInspectionInterface {
    * @param \Drupal\tmgmt\JobInterface $job
    *   The job that should have its translation aborted.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the job could be aborted, FALSE otherwise.
    */
   public function abortTranslation(JobInterface $job);
diff --git a/tmgmt.module b/tmgmt.module
index 9f140e4..a38ae70 100644
--- a/tmgmt.module
+++ b/tmgmt.module
@@ -406,7 +406,7 @@ function tmgmt_translator_load_available($job) {
  * @param $translator
  *   The machine-readable name of a translator.
  *
- * @return boolean
+ * @return bool
  *   TRUE if the translator is busy, FALSE otherwise.
  */
 function tmgmt_translator_busy($translator) {
diff --git a/tmgmt_test/tmgmt_test.routing.yml b/tmgmt_test/tmgmt_test.routing.yml
index a7f7cea..d888e89 100644
--- a/tmgmt_test/tmgmt_test.routing.yml
+++ b/tmgmt_test/tmgmt_test.routing.yml
@@ -3,4 +3,4 @@ tmgmt_test.add_to_cart:
   defaults:
     _controller: 'Drupal\tmgmt_test\TestController::addToCart'
   requirements:
-    _access: 'TRUE'
+    _access: 'true'
diff --git a/translators/tmgmt_file/src/Plugin/tmgmt_file/Format/Xliff.php b/translators/tmgmt_file/src/Plugin/tmgmt_file/Format/Xliff.php
index 1df29f7..8ce3df0 100644
--- a/translators/tmgmt_file/src/Plugin/tmgmt_file/Format/Xliff.php
+++ b/translators/tmgmt_file/src/Plugin/tmgmt_file/Format/Xliff.php
@@ -151,7 +151,7 @@ class Xliff extends \XMLWriter implements FormatInterface {
     $this->job = $job;
 
     $this->openMemory();
-    $this->setIndent(true);
+    $this->setIndent(TRUE);
     $this->setIndentString(' ');
     $this->startDocument('1.0', 'UTF-8');
 
diff --git a/translators/tmgmt_local/src/Entity/LocalTask.php b/translators/tmgmt_local/src/Entity/LocalTask.php
index ea2089e..f51d5ca 100644
--- a/translators/tmgmt_local/src/Entity/LocalTask.php
+++ b/translators/tmgmt_local/src/Entity/LocalTask.php
@@ -293,7 +293,7 @@ class LocalTask extends ContentEntityBase implements EntityChangedInterface, Ent
    * @param $status
    *   The value to check the current status against.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the passed status matches the current status, FALSE otherwise.
    */
   public function isStatus($status) {
@@ -314,7 +314,7 @@ class LocalTask extends ContentEntityBase implements EntityChangedInterface, Ent
   /**
    * Returns whether the status of this task is 'unassigned'.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the status is 'unassigned', FALSE otherwise.
    */
   public function isUnassigned() {
@@ -324,7 +324,7 @@ class LocalTask extends ContentEntityBase implements EntityChangedInterface, Ent
   /**
    * Returns whether the status of this task is 'pending'.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the status is 'pending', FALSE otherwise.
    */
   public function isPending() {
@@ -334,7 +334,7 @@ class LocalTask extends ContentEntityBase implements EntityChangedInterface, Ent
   /**
    * Returns whether the status of this task is 'completed'.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the status is 'completed', FALSE otherwise.
    */
   public function isCompleted() {
@@ -344,7 +344,7 @@ class LocalTask extends ContentEntityBase implements EntityChangedInterface, Ent
   /**
    * Returns whether the status of this task is 'rejected'.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the status is 'rejected', FALSE otherwise.
    */
   public function isRejected() {
@@ -354,7 +354,7 @@ class LocalTask extends ContentEntityBase implements EntityChangedInterface, Ent
   /**
    * Returns whether the status of this task is 'closed'.
    *
-   * @return boolean
+   * @return bool
    *   TRUE if the status is 'closed', FALSE otherwise.
    */
   public function isClosed() {
diff --git a/translators/tmgmt_local/tmgmt_local.module b/translators/tmgmt_local/tmgmt_local.module
index 17f336a..29dbfc5 100755
--- a/translators/tmgmt_local/tmgmt_local.module
+++ b/translators/tmgmt_local/tmgmt_local.module
@@ -301,7 +301,7 @@ function tmgmt_local_task_delete_multiple(array $tltids) {
  *   (Optional) The user to check for. Leave it to NULL to check for the global
  *   user.
  *
- * @return boolean
+ * @return bool
  *   TRUE if access is allowed, FALSE otherwise.
  */
 function tmgmt_local_task_access($op, $task = NULL, $account = NULL) {
@@ -338,7 +338,7 @@ function tmgmt_local_task_access($op, $task = NULL, $account = NULL) {
  *   (Optional) The user to check for. Leave it to NULL to check for the global
  *   user.
  *
- * @return boolean
+ * @return bool
  *   TRUE if access is allowed, FALSE otherwise.
  */
 function tmgmt_local_task_item_access($op, TMGMTLocalTaskItem $item = NULL, $account = NULL) {