diff --git a/config/schema/image_effects.schema.yml b/config/schema/image_effects.schema.yml
index 55c016b..58f7408 100644
--- a/config/schema/image_effects.schema.yml
+++ b/config/schema/image_effects.schema.yml
@@ -416,24 +416,27 @@ image.effect.image_effects_watermark:
   type: mapping
   label: 'Watermark image effect'
   mapping:
+    watermark_image:
+      type: string
+      label: 'Watermark image path'
+    watermark_width:
+      type: string
+      label: 'Watermark image horizontal resizing'
+    watermark_height:
+      type: string
+      label: 'Watermark image vertical resizing'
     placement:
       type: string
-      label: 'Position of the watermark'
+      label: 'Position of the watermark image on the canvas'
     x_offset:
-      type: integer
-      label: 'x offset'
+      type: string
+      label: 'X offset of the watermark image vs placement'
     y_offset:
-      type: integer
-      label: 'y offset'
+      type: string
+      label: 'Y offset of the watermark image vs placement'
     opacity:
       type: integer
       label: 'opacity'
-    watermark_image:
-      type: string
-      label: 'watermark image path'
-    watermark_scale:
-      type: integer
-      label: 'watermark image scale'
 
 image.effect.image_effects_convolution:
   type: mapping
diff --git a/image_effects.post_update.php b/image_effects.post_update.php
index 26bd1b9..8005d5d 100644
--- a/image_effects.post_update.php
+++ b/image_effects.post_update.php
@@ -59,5 +59,28 @@ function image_effects_post_update_text_overlay_strip_tags() {
 }
 
 /**
+ * Update 'watermark' effects parameters.
+ */
+function image_effects_post_update_watermark_alpha6() {
+  foreach (ImageStyle::loadMultiple() as $image_style) {
+    $edited = FALSE;
+    foreach ($image_style->getEffects() as $effect) {
+      if ($effect->getPluginId() === "image_effects_watermark") {
+        $configuration = $effect->getConfiguration();
+        if (!empty($configuration['data']['watermark_scale'])) {
+          $configuration['data']['watermark_width'] = (string) $configuration['data']['watermark_scale'] . '%';
+        }
+        unset($configuration['data']['watermark_scale']);
+        $effect->setConfiguration($configuration);
+        $edited = TRUE;
+      }
+    }
+    if ($edited) {
+      $image_style->save();
+    }
+  }
+}
+
+/**
  * @} End of "addtogroup updates-8.x-1.0-alpha".
  */
diff --git a/src/Plugin/ImageEffect/WatermarkImageEffect.php b/src/Plugin/ImageEffect/WatermarkImageEffect.php
index b3f6537..cd30d20 100644
--- a/src/Plugin/ImageEffect/WatermarkImageEffect.php
+++ b/src/Plugin/ImageEffect/WatermarkImageEffect.php
@@ -2,14 +2,15 @@
 
 namespace Drupal\image_effects\Plugin\ImageEffect;
 
+use Drupal\Core\Image\ImageFactory;
 use Drupal\Core\Image\ImageInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\image\ConfigurableImageEffectBase;
+use Drupal\image_effects\Component\ImageUtility;
 use Drupal\image_effects\Plugin\ImageEffectsPluginBaseInterface;
 use Psr\Log\LoggerInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
-use Drupal\Core\Image\ImageFactory;
 
 /**
  * Class WatermarkImageEffect.
@@ -22,6 +23,8 @@ use Drupal\Core\Image\ImageFactory;
  */
 class WatermarkImageEffect extends ConfigurableImageEffectBase implements ContainerFactoryPluginInterface {
 
+  use AnchorTrait;
+
   /**
    * The image factory service.
    *
@@ -77,12 +80,13 @@ class WatermarkImageEffect extends ConfigurableImageEffectBase implements Contai
    */
   public function defaultConfiguration() {
     return [
+      'watermark_image' => '',
+      'watermark_width' => NULL,
+      'watermark_height' => NULL,
       'placement' => 'center-center',
       'x_offset' => 0,
       'y_offset' => 0,
       'opacity' => 100,
-      'watermark_image' => '',
-      'watermark_scale' => NULL,
     ] + parent::defaultConfiguration();
   }
 
@@ -96,6 +100,9 @@ class WatermarkImageEffect extends ConfigurableImageEffectBase implements Contai
     ];
     $summary += parent::getSummary();
 
+    // Get the human readable label for placement.
+    $summary['#data']['placement'] = $this->anchorOptions()[$summary['#data']['placement']];
+
     return $summary;
   }
 
@@ -103,38 +110,54 @@ class WatermarkImageEffect extends ConfigurableImageEffectBase implements Contai
    * {@inheritdoc}
    */
   public function buildConfigurationForm(array $form, FormStateInterface $form_state) {
+    $options = [
+      '#title' => $this->t('Watermark image'),
+      '#description' => $this->t('Image to use as watermark.'),
+      '#default_value' => $this->configuration['watermark_image'],
+    ];
+    $form['watermark_image'] = $this->imageSelector->selectionElement($options);
+    $form['watermark_resize'] = [
+      '#type' => 'details',
+      '#title' => $this->t('Watermark resize'),
+      '#description' => $this->t('Select dimensions either in pixels or as percentage of the <strong>current canvas</strong>. Leaving one dimension empty will resize the watermark maintaing its aspect ratio. Leave both dimensions empty to apply the watermark in its original dimensions.'),
+      '#open' => TRUE,
+    ];
+    $form['watermark_resize']['watermark_width'] = array(
+      '#type' => 'image_effects_px_perc',
+      '#title' => $this->t('Watermark width'),
+      '#default_value' => $this->configuration['watermark_width'],
+      '#size' => 5,
+      '#maxlength' => 5,
+      '#required' => FALSE,
+    );
+    $form['watermark_resize']['watermark_height'] = array(
+      '#type' => 'image_effects_px_perc',
+      '#title' => $this->t('Watermark height'),
+      '#default_value' => $this->configuration['watermark_height'],
+      '#size' => 5,
+      '#maxlength' => 5,
+      '#required' => FALSE,
+    );
     $form['placement'] = [
       '#type' => 'radios',
       '#title' => $this->t('Placement'),
-      '#options' => [
-        'left-top' => $this->t('Top left'),
-        'center-top' => $this->t('Top center'),
-        'right-top' => $this->t('Top right'),
-        'left-center' => $this->t('Center left'),
-        'center-center' => $this->t('Center'),
-        'right-center' => $this->t('Center right'),
-        'left-bottom' => $this->t('Bottom left'),
-        'center-bottom' => $this->t('Bottom center'),
-        'right-bottom' => $this->t('Bottom right'),
-      ],
+      '#options' => $this->anchorOptions(),
       '#theme' => 'image_anchor',
       '#default_value' => $this->configuration['placement'],
-      '#description' => $this->t('Position of the watermark on the underlying image.'),
+      '#description' => $this->t('Position of the watermark on the canvas.'),
     ];
     $form['x_offset'] = [
-      '#type'  => 'number',
+      '#type'  => 'image_effects_px_perc',
       '#title' => $this->t('Horizontal offset'),
-      '#field_suffix'  => 'px',
-      '#description'   => $this->t('Additional horizontal offset from placement.'),
+      '#description'   => $this->t("Additional horizontal offset from placement. Enter a value, and specify if pixels or percent of the canvas width. '+' or no sign shifts the watermark rightward, '-' sign leftward."),
       '#default_value' => $this->configuration['x_offset'],
       '#maxlength' => 4,
       '#size' => 4,
     ];
     $form['y_offset'] = [
-      '#type'  => 'number',
+      '#type'  => 'image_effects_px_perc',
       '#title' => $this->t('Vertical offset'),
-      '#field_suffix'  => 'px',
-      '#description'   => $this->t('Additional vertical offset from placement.'),
+      '#description'   => $this->t("Additional vertical offset from placement. Enter a value, and specify if pixels or percent of the canvas height. '+' or no sign shifts the watermark downward, '-' sign upward."),
       '#default_value' => $this->configuration['y_offset'],
       '#maxlength' => 4,
       '#size' => 4,
@@ -143,29 +166,13 @@ class WatermarkImageEffect extends ConfigurableImageEffectBase implements Contai
       '#type' => 'number',
       '#title' => $this->t('Opacity'),
       '#field_suffix' => '%',
-      '#description' => $this->t('Opacity: 0 - 100'),
+      '#description' => $this->t('Opacity, in percentage, of the watermark on the canvas. 0% is fully transparent, 100% is fully opaque.'),
       '#default_value' => $this->configuration['opacity'],
       '#min' => 0,
       '#max' => 100,
       '#maxlength' => 3,
       '#size' => 3,
     ];
-    $options = [
-      '#title' => $this->t('File name'),
-      '#description' => $this->t('Image to use for watermark effect.'),
-      '#default_value' => $this->configuration['watermark_image'],
-    ];
-    $form['watermark_image'] = $this->imageSelector->selectionElement($options);
-    $form['watermark_scale'] = [
-      '#type' => 'number',
-      '#title' => $this->t('Scale'),
-      '#field_suffix' => '%',
-      '#description' => $this->t('Scales the overlay image with respect to the source image. Leave empty to use the actual size of the overlay image.'),
-      '#default_value' => $this->configuration['watermark_scale'],
-      '#min' => 1,
-      '#maxlength' => 4,
-      '#size' => 4,
-    ];
     return $form;
   }
 
@@ -174,42 +181,59 @@ class WatermarkImageEffect extends ConfigurableImageEffectBase implements Contai
    */
   public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
     parent::submitConfigurationForm($form, $form_state);
+    $this->configuration['watermark_image'] = $form_state->getValue('watermark_image');
+    $this->configuration['watermark_width'] = $form_state->getValue(['watermark_resize', 'watermark_width']);
+    $this->configuration['watermark_height'] = $form_state->getValue(['watermark_resize', 'watermark_height']);
     $this->configuration['placement'] = $form_state->getValue('placement');
     $this->configuration['x_offset'] = $form_state->getValue('x_offset');
     $this->configuration['y_offset'] = $form_state->getValue('y_offset');
     $this->configuration['opacity'] = $form_state->getValue('opacity');
-    $this->configuration['watermark_image'] = $form_state->getValue('watermark_image');
-    $this->configuration['watermark_scale'] = $form_state->getValue('watermark_scale');
   }
 
   /**
    * {@inheritdoc}
    */
   public function applyEffect(ImageInterface $image) {
+    // Get the watermark image object.
     $watermark_image = $this->imageFactory->get($this->configuration['watermark_image']);
     if (!$watermark_image->isValid()) {
       $this->logger->error('Image watermark failed using the %toolkit toolkit on %path', ['%toolkit' => $image->getToolkitId(), '%path' => $this->configuration['watermark_image']]);
       return FALSE;
     }
-    if ($this->configuration['watermark_scale'] !== NULL && $this->configuration['watermark_scale'] > 0) {
-      // Scale the overlay with respect to the dimensions of the source being
-      // overlaid. To maintain the aspect ratio, only the width of the overlay
-      // is scaled like that, the height of the overlay follows the aspect
-      // ratio.
-      $overlay_w = round($image->getWidth() * $this->configuration['watermark_scale'] / 100);
-      if (!$watermark_image->scale($overlay_w, NULL, TRUE)) {
-        return FALSE;
+
+    // Determine watermark dimensions if they need to be changed.
+    if ((bool) $this->configuration['watermark_width'] || (bool) $this->configuration['watermark_height']) {
+      $watermark_aspect = $watermark_image->getHeight() / $watermark_image->getWidth();
+      $watermark_width = ImageUtility::percentFilter($this->configuration['watermark_width'], $image->getWidth());
+      $watermark_height = ImageUtility::percentFilter($this->configuration['watermark_height'], $image->getHeight());
+      if ($watermark_width && !$watermark_height) {
+        $watermark_height = (int) round($watermark_width * $watermark_aspect);
+      }
+      elseif (!$watermark_width && $watermark_height) {
+        $watermark_width = (int) round($watermark_height / $watermark_aspect);
       }
     }
+    else {
+      $watermark_width = $watermark_image->getWidth();
+      $watermark_height = $watermark_image->getHeight();
+    }
+
+    // Calculate position of watermark on source image based on placement option.
     list($x, $y) = explode('-', $this->configuration['placement']);
-    $x_pos = round(image_filter_keyword($x, $image->getWidth(), $watermark_image->getWidth()));
-    $y_pos = round(image_filter_keyword($y, $image->getHeight(), $watermark_image->getHeight()));
+    $x_pos = round(image_filter_keyword($x, $image->getWidth(), $watermark_width));
+    $y_pos = round(image_filter_keyword($y, $image->getHeight(), $watermark_height));
+
+    // Calculate offset based on px/percentage.
+    $x_offset = ImageUtility::percentFilter($this->configuration['x_offset'], $image->getWidth());
+    $y_offset = ImageUtility::percentFilter($this->configuration['y_offset'], $image->getHeight());
 
     return $image->apply('watermark', [
-      'x_offset' => $x_pos + $this->configuration['x_offset'],
-      'y_offset' => $y_pos + $this->configuration['y_offset'],
-      'opacity' => $this->configuration['opacity'],
       'watermark_image' => $watermark_image,
+      'watermark_width' => $watermark_width !== $watermark_image->getWidth() ? $watermark_width : NULL,
+      'watermark_height' => $watermark_height !== $watermark_image->getHeight() ? $watermark_height : NULL,
+      'x_offset' => $x_pos + $x_offset,
+      'y_offset' => $y_pos + $y_offset,
+      'opacity' => $this->configuration['opacity'],
     ]);
   }
 
diff --git a/src/Plugin/ImageToolkit/Operation/WatermarkTrait.php b/src/Plugin/ImageToolkit/Operation/WatermarkTrait.php
index d5aca7a..cbf8ac6 100644
--- a/src/Plugin/ImageToolkit/Operation/WatermarkTrait.php
+++ b/src/Plugin/ImageToolkit/Operation/WatermarkTrait.php
@@ -14,20 +14,34 @@ trait WatermarkTrait {
    */
   protected function arguments() {
     return [
+      'watermark_image' => [
+        'description' => 'Watermark image.',
+      ],
+      'watermark_width' => [
+        'description' => 'Width of watermark image.',
+        'required' => FALSE,
+        'default' => NULL,
+      ],
+      'watermark_height' => [
+        'description' => 'Height of watermark image.',
+        'required' => FALSE,
+        'default' => NULL,
+      ],
       'x_offset' => [
         'description' => 'X offset for watermark image.',
+        'required' => FALSE,
+        'default' => 0,
       ],
       'y_offset' => [
         'description' => 'Y offset for watermark image.',
+        'required' => FALSE,
+        'default' => 0,
       ],
       'opacity' => [
         'description' => 'Opacity for watermark image.',
         'required' => FALSE,
         'default' => 100,
       ],
-      'watermark_image' => [
-        'description' => 'Image to use for watermark effect.',
-      ],
     ];
   }
 
@@ -48,6 +62,26 @@ trait WatermarkTrait {
       $source = $arguments['watermark_image']->getSource();
       throw new \InvalidArgumentException("Invalid image at {$source}");
     }
+    // Ensure 'watermark_width' is NULL or a positive integer.
+    $arguments['watermark_width'] = $arguments['watermark_width'] !== NULL ? (int) $arguments['watermark_width'] : NULL;
+    if ($arguments['watermark_width'] !== NULL && $arguments['watermark_width'] <= 0) {
+      throw new \InvalidArgumentException("Invalid watermark width ('{$arguments['watermark_width']}') specified for the image 'watermark' operation");
+    }
+    // Ensure 'watermark_height' is NULL or a positive integer.
+    $arguments['watermark_height'] = $arguments['watermark_height'] !== NULL ? (int) $arguments['watermark_height'] : NULL;
+    if ($arguments['watermark_height'] !== NULL && $arguments['watermark_height'] <= 0) {
+      throw new \InvalidArgumentException("Invalid height ('{$arguments['watermark_height']}') specified for the image 'watermark' operation");
+    }
+    // Ensure 'x_offset' is a positive integer.
+    $arguments['x_offset'] = (int) $arguments['x_offset'];
+    if ($arguments['x_offset'] < 0) {
+      throw new \InvalidArgumentException("Invalid X offset ('{$arguments['x_offset']}') specified for the image 'watermark' operation");
+    }
+    // Ensure 'y_offset' is a positive integer.
+    $arguments['y_offset'] = (int) $arguments['y_offset'];
+    if ($arguments['y_offset'] < 0) {
+      throw new \InvalidArgumentException("Invalid Y offset ('{$arguments['y_offset']}') specified for the image 'watermark' operation");
+    }
     return $arguments;
   }
 
diff --git a/src/Plugin/ImageToolkit/Operation/gd/Watermark.php b/src/Plugin/ImageToolkit/Operation/gd/Watermark.php
index 05eb60d..5b6a4e8 100644
--- a/src/Plugin/ImageToolkit/Operation/gd/Watermark.php
+++ b/src/Plugin/ImageToolkit/Operation/gd/Watermark.php
@@ -25,15 +25,22 @@ class Watermark extends GDImageToolkitOperationBase {
    * {@inheritdoc}
    */
   protected function execute(array $arguments) {
+    $watermark = $arguments['watermark_image'];
+
+    // Resize watermark if needed.
+    if ($arguments['watermark_width'] || $arguments['watermark_height']) {
+      $watermark->apply('resize', ['width' => $arguments['watermark_width'], 'height' => $arguments['watermark_height']]);
+    }
+
     return $this->imageCopyMergeAlpha(
       $this->getToolkit()->getResource(),
-      $arguments['watermark_image']->getToolkit()->getResource(),
+      $watermark->getToolkit()->getResource(),
       $arguments['x_offset'],
       $arguments['y_offset'],
       0,
       0,
-      $arguments['watermark_image']->getToolkit()->getWidth(),
-      $arguments['watermark_image']->getToolkit()->getHeight(),
+      $watermark->getToolkit()->getWidth(),
+      $watermark->getToolkit()->getHeight(),
       $arguments['opacity']
     );
   }
diff --git a/src/Plugin/ImageToolkit/Operation/imagemagick/Watermark.php b/src/Plugin/ImageToolkit/Operation/imagemagick/Watermark.php
index f35fba6..ee7d268 100644
--- a/src/Plugin/ImageToolkit/Operation/imagemagick/Watermark.php
+++ b/src/Plugin/ImageToolkit/Operation/imagemagick/Watermark.php
@@ -24,7 +24,7 @@ class Watermark extends ImagemagickImageToolkitOperationBase {
    * {@inheritdoc}
    */
   protected function execute(array $arguments) {
-    // Overlay image local path.
+    // Watermark image local path.
     $local_path = $arguments['watermark_image']->getToolkit()->getSourceLocalPath();
     if ($local_path !== '') {
       $image_path = $this->getToolkit()->escapeShellArg($local_path);
@@ -34,11 +34,9 @@ class Watermark extends ImagemagickImageToolkitOperationBase {
       throw new \InvalidArgumentException("Missing local path for image at {$source_path}");
     }
 
-    // Set the dimensions of the overlay. Use of the scale option means that we
-    // need to change the dimensions: always set them, they don't harm when the
-    // scale option is not used.
-    $w = $arguments['watermark_image']->getWidth();
-    $h = $arguments['watermark_image']->getHeight();
+    // Set the dimensions of the overlay.
+    $w = $arguments['watermark_width'] ?: $arguments['watermark_image']->getToolkit()->getWidth();
+    $h = $arguments['watermark_height'] ?: $arguments['watermark_image']->getToolkit()->getHeight();
 
     // Set offset. Offset arguments require a sign in front.
     $x = $arguments['x_offset'] >= 0 ? ('+' . $arguments['x_offset']) : $arguments['x_offset'];
diff --git a/src/Tests/Update/WatermarkUpdateTest.php b/src/Tests/Update/WatermarkUpdateTest.php
new file mode 100644
index 0000000..dd8d981
--- /dev/null
+++ b/src/Tests/Update/WatermarkUpdateTest.php
@@ -0,0 +1,73 @@
+<?php
+
+namespace Drupal\image_effects\Tests\Update;
+
+use Drupal\system\Tests\Update\UpdatePathTestBase;
+
+/**
+ * Tests the upgrade path for 'watermark' effect.
+ *
+ * @see image_effects_post_update_watermark_alpha6()
+ *
+ * @group Image Effects
+ */
+class WatermarkUpdateTest extends UpdatePathTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = ['image_effects'];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setDatabaseDumpFiles() {
+    $this->databaseDumpFiles = [
+      __DIR__ . '/../../../tests/fixtures/update/d_820_ie_810a2.php.gz',
+      __DIR__ . '/../../../tests/fixtures/update/test_watermark.php',
+    ];
+  }
+
+  /**
+   * Tests that 'Watermark' effects are updated properly.
+   */
+  public function testWatermarkUpdate() {
+    // Test that Watermark effect has parameters as valid before
+    // 8.x-1.0-alpha6.
+    $effect_data = $this->config('image.style.test_watermark_scale')->get('effects.3d493386-5251-4d45-b395-2e036f7203c0.data');
+    $this->assertFalse(array_key_exists('watermark_width', $effect_data));
+    $this->assertFalse(array_key_exists('watermark_height', $effect_data));
+    $this->assertIdentical(10, $effect_data['x_offset']);
+    $this->assertIdentical(10, $effect_data['y_offset']);
+    $this->assertIdentical(20, $effect_data['watermark_scale']);
+
+    $effect_data = $this->config('image.style.test_watermark_no_scale')->get('effects.253dcaa0-27f0-49ef-9d5f-4bda9bf78ff7.data');
+    $this->assertFalse(array_key_exists('watermark_width', $effect_data));
+    $this->assertFalse(array_key_exists('watermark_height', $effect_data));
+    $this->assertIdentical(10, $effect_data['x_offset']);
+    $this->assertIdentical(10, $effect_data['y_offset']);
+    $this->assertNull($effect_data['watermark_scale']);
+
+    // Run updates.
+    $this->runUpdates();
+
+    // Test that Watermark effect has parameters as introduced in
+    // 8.x-1.0-alpha6.
+    $effect_data = $this->config('image.style.test_watermark_scale')->get('effects.3d493386-5251-4d45-b395-2e036f7203c0.data');
+    $this->assertTrue(array_key_exists('watermark_width', $effect_data));
+    $this->assertTrue(array_key_exists('watermark_height', $effect_data));
+    $this->assertIdentical('10', $effect_data['x_offset']);
+    $this->assertIdentical('10', $effect_data['y_offset']);
+    $this->assertIdentical('20%', $effect_data['watermark_width']);
+    $this->assertFalse(array_key_exists('watermark_scale', $effect_data));
+
+    $effect_data = $this->config('image.style.test_watermark_no_scale')->get('effects.253dcaa0-27f0-49ef-9d5f-4bda9bf78ff7.data');
+    $this->assertTrue(array_key_exists('watermark_width', $effect_data));
+    $this->assertTrue(array_key_exists('watermark_height', $effect_data));
+    $this->assertIdentical('10', $effect_data['x_offset']);
+    $this->assertIdentical('10', $effect_data['y_offset']);
+    $this->assertNull($effect_data['watermark_width']);
+    $this->assertFalse(array_key_exists('watermark_scale', $effect_data));
+  }
+
+}
diff --git a/templates/image-effects-watermark-summary.html.twig b/templates/image-effects-watermark-summary.html.twig
index df2c96f..2578ba5 100644
--- a/templates/image-effects-watermark-summary.html.twig
+++ b/templates/image-effects-watermark-summary.html.twig
@@ -5,12 +5,13 @@
  *
  * Available variables:
  * - data: The current configuration for this watermark effect, including:
+ *   - watermark_image: The watermark image.
+ *   - watermark_width: The watermark image width.
+ *   - watermark_height: The watermark image height.
  *   - placement: The position of the watermark on the underlying image.
  *   - x_offset: The x_offset of the watermark image.
  *   - y_offset: The y_offset of the watermark image.
  *   - opacity: The opacity of the watermark image.
- *   - watermark_image: The watermark image.
- *   - watermark_scale: The watermark image scale.
  * - effect: The effect information, including:
  *   - id: The effect identifier.
  *   - label: The effect name.
@@ -20,10 +21,15 @@
  */
 #}
 {% spaceless %}
-  - {{ 'Image'|t }}: <strong>{{ data.watermark_image|e }}</strong>,
-    {% if data.watermark_scale %}{{ 'Scale'|t }}: {{ data.watermark_scale|e }}%,{% endif %}
-    {{ 'Placement'|t }}: {{ data.placement|e }},
-    {% if data.x_offset %}{{ 'X offset'|t }}: {{ data.x_offset|e }}px,{% endif %}
-    {% if data.y_offset %}{{ 'Y offset'|t }}: {{ data.y_offset|e }}px,{% endif %}
-    {{ 'Opacity'|t }}: {{ data.opacity|e }}%
+  - {{ 'Image'|t }}: <strong>{{ data.watermark_image|e }}</strong>
+  {% if data.watermark_width or data.watermark_height %}
+    - {{ 'Watermark width'|t }}:
+    {% if data.watermark_width %}{{ data.watermark_width|e }}{% else %}{{ '(scaled)'|t }}{% endif %},
+    {{ 'height'|t }}:
+    {% if data.watermark_height %}{{ data.watermark_height|e }}{% else %}{{ '(scaled)'|t }}{% endif %}
+  {% endif %}
+  - {{ 'Placement'|t }}: {{ data.placement|e }}
+  {% if data.x_offset %}- {{ 'X offset'|t }}: {{ data.x_offset|e }}{% endif %}
+  {% if data.y_offset %}- {{ 'Y offset'|t }}: {{ data.y_offset|e }}{% endif %}
+  - {{ 'Opacity'|t }}: {{ data.opacity|e }}%
 {% endspaceless %}
diff --git a/tests/fixtures/update/image.style.test_watermark_no_scale.yml b/tests/fixtures/update/image.style.test_watermark_no_scale.yml
new file mode 100644
index 0000000..8af8961
--- /dev/null
+++ b/tests/fixtures/update/image.style.test_watermark_no_scale.yml
@@ -0,0 +1,20 @@
+uuid: 2ab09231-1e24-4f11-809a-6f4e9e8f2793
+langcode: en
+status: true
+dependencies:
+  module:
+    - image_effects
+name: test_watermark_no_scale
+label: test_watermark_no_scale
+effects:
+  253dcaa0-27f0-49ef-9d5f-4bda9bf78ff7:
+    uuid: 253dcaa0-27f0-49ef-9d5f-4bda9bf78ff7
+    id: image_effects_watermark
+    weight: 1
+    data:
+      placement: center-center
+      x_offset: 10
+      y_offset: 10
+      opacity: 100
+      watermark_image: 'public://image-test.png'
+      watermark_scale: null
diff --git a/tests/fixtures/update/image.style.test_watermark_scale.yml b/tests/fixtures/update/image.style.test_watermark_scale.yml
new file mode 100644
index 0000000..64c6c97
--- /dev/null
+++ b/tests/fixtures/update/image.style.test_watermark_scale.yml
@@ -0,0 +1,20 @@
+uuid: d3f9440c-5ec8-4204-b958-4df8f62b7b03
+langcode: en
+status: true
+dependencies:
+  module:
+    - image_effects
+name: test_watermark_scale
+label: test_watermark_scale
+effects:
+  3d493386-5251-4d45-b395-2e036f7203c0:
+    uuid: 3d493386-5251-4d45-b395-2e036f7203c0
+    id: image_effects_watermark
+    weight: 1
+    data:
+      placement: center-center
+      x_offset: 10
+      y_offset: 10
+      opacity: 100
+      watermark_image: 'public://image-test.png'
+      watermark_scale: 20
diff --git a/tests/fixtures/update/test_watermark.php b/tests/fixtures/update/test_watermark.php
new file mode 100644
index 0000000..a287788
--- /dev/null
+++ b/tests/fixtures/update/test_watermark.php
@@ -0,0 +1,21 @@
+<?php
+
+/**
+ * @file
+ * Test fixture for image style with watermark effect.
+ */
+
+use Drupal\Core\Database\Database;
+use Drupal\Core\Serialization\Yaml;
+
+$connection = Database::getConnection();
+
+foreach (['image.style.test_watermark_scale', 'image.style.test_watermark_no_scale'] as $style) {
+  $connection->insert('config')
+    ->fields(array(
+      'collection' => '',
+      'name' => $style,
+      'data' => serialize(Yaml::decode(file_get_contents('modules/image_effects/tests/fixtures/update/' . $style . '.yml'))),
+    ))
+    ->execute();
+}
diff --git a/tests/src/Functional/Effect/WatermarkTest.php b/tests/src/Functional/Effect/WatermarkTest.php
index dcfdcb9..274f0c5 100644
--- a/tests/src/Functional/Effect/WatermarkTest.php
+++ b/tests/src/Functional/Effect/WatermarkTest.php
@@ -42,11 +42,13 @@ class WatermarkTest extends ImageEffectsTestBase {
     $effect = [
       'id' => 'image_effects_watermark',
       'data' => [
+        'watermark_image' => $watermark_uri,
         'placement' => 'left-top',
-        'x_offset' => 1,
-        'y_offset' => 1,
+        'x_offset][c0][c1][value' => 1,
+        'x_offset][c0][c1][uom' => 'px',
+        'y_offset][c0][c1][value' => 1,
+        'y_offset][c0][c1][uom' => 'px',
         'opacity' => 100,
-        'watermark_image' => $watermark_uri,
       ],
     ];
     $uuid = $this->addEffectToTestStyle($effect);
@@ -74,12 +76,13 @@ class WatermarkTest extends ImageEffectsTestBase {
     $effect = [
       'id' => 'image_effects_watermark',
       'data' => [
+        'watermark_image' => $watermark_uri,
         'placement' => 'left-top',
-        'x_offset' => 0,
-        'y_offset' => 0,
+        'x_offset][c0][c1][value' => NULL,
+        'y_offset][c0][c1][value' => NULL,
         'opacity' => 100,
-        'watermark_image' => $watermark_uri,
-        'watermark_scale' => 5,
+        'watermark_resize][watermark_width][c0][c1][value' => 5,
+        'watermark_resize][watermark_width][c0][c1][uom' => 'perc',
       ],
     ];
     $uuid = $this->addEffectToTestStyle($effect);
@@ -107,11 +110,11 @@ class WatermarkTest extends ImageEffectsTestBase {
     $effect = [
       'id' => 'image_effects_watermark',
       'data' => [
+        'watermark_image' => $watermark_uri,
         'placement' => 'left-top',
-        'x_offset' => 0,
-        'y_offset' => 0,
+        'x_offset][c0][c1][value' => NULL,
+        'y_offset][c0][c1][value' => NULL,
         'opacity' => 100,
-        'watermark_image' => $watermark_uri,
       ],
     ];
     $uuid = $this->addEffectToTestStyle($effect);
@@ -141,11 +144,11 @@ class WatermarkTest extends ImageEffectsTestBase {
     $effect = [
       'id' => 'image_effects_watermark',
       'data' => [
+        'watermark_image' => $watermark_uri,
         'placement' => 'left-top',
-        'x_offset' => 0,
-        'y_offset' => 0,
+        'x_offset][c0][c1][value' => NULL,
+        'y_offset][c0][c1][value' => NULL,
         'opacity' => 50,
-        'watermark_image' => $watermark_uri,
       ],
     ];
     $uuid = $this->addEffectToTestStyle($effect);