diff --git a/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php b/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php
index 2a868db..003cd57 100644
--- a/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php
+++ b/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php
@@ -102,10 +102,7 @@ public function get($index) {
     if (!is_numeric($index)) {
       throw new \InvalidArgumentException('Unable to get a value with a non-numeric delta in a list.');
     }
-    // Automatically create the first item for computed fields.
-    if ($index == 0 && !isset($this->list[0]) && $this->definition->isComputed()) {
-      $this->list[0] = $this->createItem(0);
-    }
+
     return isset($this->list[$index]) ? $this->list[$index] : NULL;
   }
 
diff --git a/core/modules/field/tests/modules/field_computed_test/field_computed_test.info.yml b/core/modules/field/tests/modules/field_computed_test/field_computed_test.info.yml
new file mode 100644
index 0000000..42f6216
--- /dev/null
+++ b/core/modules/field/tests/modules/field_computed_test/field_computed_test.info.yml
@@ -0,0 +1,6 @@
+name: 'Field Computed Test'
+type: module
+description: 'Support module for the computed field tests.'
+core: 8.x
+package: Testing
+version: VERSION
diff --git a/core/modules/field/tests/modules/field_computed_test/field_computed_test.module b/core/modules/field/tests/modules/field_computed_test/field_computed_test.module
new file mode 100644
index 0000000..941cdfe
--- /dev/null
+++ b/core/modules/field/tests/modules/field_computed_test/field_computed_test.module
@@ -0,0 +1,37 @@
+<?php
+
+use Drupal\Core\Entity\EntityTypeInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
+
+function field_computed_test_entity_base_field_info(EntityTypeInterface $entity) {
+  if ($entity->id() === 'node') {
+    $fields = array();
+
+    $fields['field_dice_count'] = BaseFieldDefinition::create('integer')
+      ->setCustomStorage(false)
+      ->setLabel(t('Dice count'))
+      ->setDisplayOptions('view', array(
+        'label' => 'inline',
+        'type' => 'text_textfield',
+        'weight' => 0,
+      ))
+      ->setDisplayOptions('form', array(
+        'type' => 'integer',
+        'weight' => 10,
+      ))
+      ->setDisplayConfigurable('form', TRUE);
+
+    $fields['field_dice_result'] = BaseFieldDefinition::create('integer')
+      ->setLabel(t('Dice result'))
+      ->setComputed(TRUE)
+      ->setClass('\Drupal\field_computed_test\Plugin\Field\FieldType\DiceFieldItemList')
+      ->setDisplayOptions('view', array(
+        'label' => 'inline',
+        'type' => 'number_integer',
+        'weight' => 0,
+      ));
+
+    return $fields;
+  }
+
+}
diff --git a/core/modules/field/tests/modules/field_computed_test/src/Plugin/Field/FieldType/DiceFieldItemList.php b/core/modules/field/tests/modules/field_computed_test/src/Plugin/Field/FieldType/DiceFieldItemList.php
new file mode 100644
index 0000000..242ade0
--- /dev/null
+++ b/core/modules/field/tests/modules/field_computed_test/src/Plugin/Field/FieldType/DiceFieldItemList.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Drupal\field_computed_test\Plugin\Field\FieldType;
+
+use Drupal\Core\Field\FieldItemList;
+
+/**
+ * Represents a configurable dice result.
+ */
+class DiceFieldItemList extends FieldItemList {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getValue($include_computed = FALSE) {
+    $items_count = $this->getParent()->getValue()->field_dice_count->value;
+    $values = array();
+    foreach (range(0, $items_count - 1) as $delta) {
+      $values[$delta] = rand(1, 6);
+    }
+    return $values;
+  }
+
+  /**
+   * Implements \Countable::count().
+   */
+  public function count() {
+    $items_count = $this->getParent()->getValue()->field_dice_count->value;
+    return $items_count;
+  }
+}