.../src/Plugin/DataType/ComputedImageStyle.php     | 20 ++++++++++++++++--
 .../src/Plugin/DataType/ComputedImageStyleList.php |  9 ++++++++
 .../Plugin/DataType/ImageStyleDataDefinition.php   | 24 ++++++++++++++++++++++
 3 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/core/modules/image/src/Plugin/DataType/ComputedImageStyle.php b/core/modules/image/src/Plugin/DataType/ComputedImageStyle.php
index 8caacd5..0bb862c 100644
--- a/core/modules/image/src/Plugin/DataType/ComputedImageStyle.php
+++ b/core/modules/image/src/Plugin/DataType/ComputedImageStyle.php
@@ -2,7 +2,9 @@
 
 namespace Drupal\image\Plugin\DataType;
 
-use Drupal\Core\TypedData\TypedData;
+use Drupal\Core\TypedData\DataDefinition;
+use Drupal\Core\TypedData\MapDataDefinition;
+use Drupal\Core\TypedData\Plugin\DataType\Map;
 
 /**
  * The image style data type.
@@ -12,6 +14,7 @@
  * @DataType(
  *   id = "image_style",
  *   label = @Translation("Image style metadata"),
+ *   definition_class = "\Drupal\image\Plugin\DataType\ImageStyleDataDefinition",
  *   list_class = "\Drupal\image\Plugin\DataType\ComputedImageStyleList",
  * )
  *
@@ -19,7 +22,7 @@
  *
  * @internal
  */
-class ComputedImageStyle extends TypedData {
+class ComputedImageStyle extends Map {
 
   protected $url = NULL;
   protected $width = NULL;
@@ -28,6 +31,19 @@ class ComputedImageStyle extends TypedData {
   /**
    * {@inheritdoc}
    *
+   * @todo ensure this is actually used, and make typed data stuff actually work. Should it be this or should it be \Drupal\image\Plugin\DataType\ImageStyleDataDefinition? I can't figure it out.
+   */
+  public function getDataDefinition() {
+    return MapDataDefinition::create()
+      ->setPropertyDefinition('url', DataDefinition::create('uri'))
+      ->setPropertyDefinition('width', DataDefinition::create('int'))
+      ->setPropertyDefinition('height', DataDefinition::create('int'));
+  }
+
+
+  /**
+   * {@inheritdoc}
+   *
    * @todo receive a value object that implements CacheableDependencyInterface
    */
   public function setValue($value, $notify = TRUE) {
diff --git a/core/modules/image/src/Plugin/DataType/ComputedImageStyleList.php b/core/modules/image/src/Plugin/DataType/ComputedImageStyleList.php
index 6343ca2..513af43 100644
--- a/core/modules/image/src/Plugin/DataType/ComputedImageStyleList.php
+++ b/core/modules/image/src/Plugin/DataType/ComputedImageStyleList.php
@@ -32,6 +32,15 @@ protected function computedListProperty() {
   }
 
   /**
+   * {@inheritdoc}
+   */
+  protected function createItem($offset = 0, $value = NULL) {
+    // @todo perhaps some override like \Drupal\Core\Field\FieldItemList::createItem()?
+    return parent::createItem($offset, $value);
+  }
+
+
+  /**
    * @param \Drupal\file\FileInterface $file
    * @param $width
    * @param $height
diff --git a/core/modules/image/src/Plugin/DataType/ImageStyleDataDefinition.php b/core/modules/image/src/Plugin/DataType/ImageStyleDataDefinition.php
new file mode 100644
index 0000000..b48f5ce
--- /dev/null
+++ b/core/modules/image/src/Plugin/DataType/ImageStyleDataDefinition.php
@@ -0,0 +1,24 @@
+<?php
+
+namespace Drupal\image\Plugin\DataType;
+
+use Drupal\Core\TypedData\DataDefinition;
+use Drupal\Core\TypedData\MapDataDefinition;
+
+/**
+ * @todo perhaps this should not exist, and we should have \Drupal\image\Plugin\DataType\ComputedImageStyle::getDataDefinition() instead? I can't figure it out.
+ */
+class ImageStyleDataDefinition extends MapDataDefinition {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getPropertyDefinitions() {
+    return [
+      'url' => DataDefinition::create('uri'),
+      'width' => DataDefinition::create('int'),
+      'height' => DataDefinition::create('int'),
+    ];
+  }
+
+}