diff --git a/radioactivity.services.yml b/radioactivity.services.yml
index 38ec0a6..9d78e93 100644
--- a/radioactivity.services.yml
+++ b/radioactivity.services.yml
@@ -1,7 +1,7 @@
 services:
   radioactivity.processor:
     class: Drupal\radioactivity\RadioactivityProcessor
-    arguments: ["@entity_type.manager", "@state", "@logger.factory", "@radioactivity.storage"]
+    arguments: ["@entity_type.manager", "@state", "@logger.factory", "@radioactivity.storage", "@datetime:time"]
 
   radioactivity.storage:
 
diff --git a/src/Plugin/Field/FieldType/RadioactivityField.php b/src/Plugin/Field/FieldType/RadioactivityField.php
index 18965f4..b105b69 100644
--- a/src/Plugin/Field/FieldType/RadioactivityField.php
+++ b/src/Plugin/Field/FieldType/RadioactivityField.php
@@ -102,7 +102,7 @@ class RadioactivityField extends FieldItemBase {
    */
   public static function generateSampleValue(FieldDefinitionInterface $field_definition) {
     $values['energy'] = 1;
-    $values['timestamp'] = REQUEST_TIME;
+    $values['timestamp'] = \Drupal::time()->getRequestTime();
     return $values;
   }
 
@@ -177,7 +177,7 @@ Decay: Energy increases by the emission amount. Decreases 50% per half-life time
     if (!$this->energy) {
       $this->energy = 0;
     }
-    $this->timestamp = REQUEST_TIME;
+    $this->timestamp = \Drupal::time()->getRequestTime();
   }
 
   /**
diff --git a/src/Plugin/Field/FieldWidget/RadioactivityEnergy.php b/src/Plugin/Field/FieldWidget/RadioactivityEnergy.php
index aabe852..519706e 100644
--- a/src/Plugin/Field/FieldWidget/RadioactivityEnergy.php
+++ b/src/Plugin/Field/FieldWidget/RadioactivityEnergy.php
@@ -25,7 +25,7 @@ class RadioactivityEnergy extends WidgetBase {
   public static function defaultSettings() {
     return [
       'energy' => 0.0,
-      'timestamp' => REQUEST_TIME,
+      'timestamp' => \Drupal::time()->getRequestTime(),
     ] + parent::defaultSettings();
   }
 
@@ -44,7 +44,7 @@ class RadioactivityEnergy extends WidgetBase {
     // @todo Should timestamp be configurable? See https://www.drupal.org/node/2677688
     // $element['timestamp'] = [
     //   '#type' => 'hidden',
-    //   '#default_value' => REQUEST_TIME;
+    //   '#default_value' => \Drupal::time()->getRequestTime();
     // ];
 
     // Put the form element into the form's "advanced" group.
diff --git a/src/RadioactivityProcessor.php b/src/RadioactivityProcessor.php
index 00bea2a..c8b931b 100644
--- a/src/RadioactivityProcessor.php
+++ b/src/RadioactivityProcessor.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\radioactivity;
 
+use Drupal\Component\Datetime\TimeInterface;
 use Drupal\Core\Entity\EntityTypeManager;
 use Drupal\Core\State\State;
 use Drupal\Core\Logger\LoggerChannelFactoryInterface;
@@ -43,6 +44,13 @@ class RadioactivityProcessor implements RadioactivityProcessorInterface {
   protected $storage;
 
   /**
+   * The timestamp for the current request.
+   *
+   * @var integer
+   */
+  protected $requestTime;
+
+  /**
    * Constructs a Radioactivity processor.
    *
    * @param \Drupal\Core\Entity\EntityTypeManager $entity_type_manager
@@ -52,12 +60,16 @@ class RadioactivityProcessor implements RadioactivityProcessorInterface {
    * @param \Drupal\Core\Logger\LoggerChannelFactoryInterface $logger_factory
    *   The logger.
    * @param \Drupal\radioactivity\StorageFactory $storage
+   *   The storage factory service.
+   * @param \Drupal\Component\Datetime\TimeInterface $time
+   *   The time service.
    */
-  public function __construct(EntityTypeManager $entity_type_manager, State $state, LoggerChannelFactoryInterface $logger_factory, StorageFactory $storage) {
+  public function __construct(EntityTypeManager $entity_type_manager, State $state, LoggerChannelFactoryInterface $logger_factory, StorageFactory $storage, TimeInterface $time) {
     $this->entityTypeManager = $entity_type_manager;
     $this->state = $state;
     $this->log = $logger_factory->get('radioactivity');
     $this->storage = $storage->getConfiguredStorage();
+    $this->requestTime = $time->getRequestTime();
   }
 
   /**
@@ -75,7 +87,7 @@ class RadioactivityProcessor implements RadioactivityProcessorInterface {
 
     $last_cron_timestamp = $this->state->get('radioactivity_last_cron_timestamp', 0);
 
-    $this->state->set('radioactivity_last_cron_timestamp', REQUEST_TIME);
+    $this->state->set('radioactivity_last_cron_timestamp', $this->requestTime);
 
     foreach ($field_storage_configs as $field_storage) {
 
@@ -113,7 +125,7 @@ class RadioactivityProcessor implements RadioactivityProcessorInterface {
     // seconds have passed since the last cron run.
     if ($profile == 'decay') {
       $threshold_timestamp = $last_cron_timestamp - ($last_cron_timestamp % $granularity) + $granularity;
-      if (REQUEST_TIME < $threshold_timestamp) {
+      if ($this->requestTime < $threshold_timestamp) {
         // Granularity not reached yet.
         return;
       }
@@ -126,7 +138,7 @@ class RadioactivityProcessor implements RadioactivityProcessorInterface {
     //   long cron cycle times. Prepare for queue processing.
     $query = $this->entityTypeManager->getStorage($entity_type)->getQuery()
       // @todo Why use timestamp in this query? See https://www.drupal.org/node/2677688
-      //->condition($field_name . '.timestamp', REQUEST_TIME, ' < ')
+      //->condition($field_name . '.timestamp', $this->requestTime, ' < ')
       ->condition($field_name . '.energy', NULL, 'IS NOT NULL');
     $nids = $query->execute();
     /** @var \Drupal\Core\Entity\ContentEntityInterface[] $entities */
@@ -136,7 +148,7 @@ class RadioactivityProcessor implements RadioactivityProcessorInterface {
     foreach ($entities as $entity) {
 
       $timestamp = $entity->{$field_name}->timestamp;
-      $elapsed = $timestamp ? REQUEST_TIME - $timestamp : 0;
+      $elapsed = $timestamp ? $this->requestTime - $timestamp : 0;
       $energy = $entity->{$field_name}->energy;
 
       switch ($profile) {
@@ -153,7 +165,7 @@ class RadioactivityProcessor implements RadioactivityProcessorInterface {
         // Set the new energy level and update the timestamp.
         $entity->{$field_name}->setValue([
           'energy' => $energy,
-          'timestamp' => REQUEST_TIME,
+          'timestamp' => $this->requestTime,
         ]);
       }
       else {