diff --git a/core/modules/image/src/Plugin/Filter/FilterImageStyle.php b/core/modules/image/src/Plugin/Filter/FilterImageStyle.php
index 7926f41..1c03de5 100644
--- a/core/modules/image/src/Plugin/Filter/FilterImageStyle.php
+++ b/core/modules/image/src/Plugin/Filter/FilterImageStyle.php
@@ -97,11 +97,12 @@ public function process($text, $langcode) {
       $dom = HTML::load($text);
       $xpath = new \DOMXPath($dom);
 
-      // Process each img element DOM node found with the necessary attributes.
-      foreach ($xpath->query('//*[@data-entity-type="file" and @data-entity-uuid and @data-image-style]') as $dom_node) {
+      // Process each img element DOM element found with the necessary attributes.
+      /** @var \DOMElement $dom_element */
+      foreach ($xpath->query('//*[@data-entity-type="file" and @data-entity-uuid and @data-image-style]') as $dom_element) {
         // Get the UUID and image style for the file.
-        $file_uuid = $dom_node->getAttribute('data-entity-uuid');
-        $image_style_id = $dom_node->getAttribute('data-image-style');
+        $file_uuid = $dom_element->getAttribute('data-entity-uuid');
+        $image_style_id = $dom_element->getAttribute('data-image-style');
 
         // If the image style is not a valid one, then don't transform the HTML.
         if (empty($file_uuid) || !in_array($image_style_id, $image_styles)) {
@@ -109,10 +110,10 @@ public function process($text, $langcode) {
         }
 
         // Transform the HTML for the img element by applying an image style.
-        $altered_html = $this->getImageStyleHtml($file_uuid, $image_style_id, $dom_node);
+        $altered_img = $this->getImageStyleHtml($file_uuid, $image_style_id, $dom_element);
 
         // Load the altered HTML into a new DOMDocument and retrieve the element.
-        $updated_node = HTML::load($altered_html)->getElementsByTagName('body')
+        $updated_node = HTML::load($altered_img)->getElementsByTagName('body')
           ->item(0)
           ->childNodes
           ->item(0);
@@ -122,7 +123,7 @@ public function process($text, $langcode) {
         $updated_node = $dom->importNode($updated_node, TRUE);
 
         // Finally, replace the original image node with the new image node.
-        $dom_node->parentNode->replaceChild($updated_node, $dom_node);
+        $dom_element->parentNode->replaceChild($updated_node, $dom_element);
       }
 
       // Process the filter with the newly updated DOM.
@@ -176,22 +177,22 @@ protected function getImageInfo($file_uuid) {
   /**
    * Removes attributes that will be generated from image style theme function.
    *
-   * @param \DOMNode $dom_node
-   *   The DOM node for the img element.
+   * @param \DOMElement $dom_element
+   *   The DOM element for the img element.
    *
    * @return array
    *  The attributes array.
    */
-  protected function prepareImageAttributes($dom_node) {
+  protected function prepareImageAttributes(\DOMElement $dom_element) {
     // Make sure all non-regenerated attributes are retained.
-    $dom_node->removeAttribute('data-entity-uuid');
-    $dom_node->removeAttribute('data-image-style');
-    $dom_node->removeAttribute('width');
-    $dom_node->removeAttribute('height');
-    $dom_node->removeAttribute('src');
+    $dom_element->removeAttribute('data-entity-uuid');
+    $dom_element->removeAttribute('data-image-style');
+    $dom_element->removeAttribute('width');
+    $dom_element->removeAttribute('height');
+    $dom_element->removeAttribute('src');
     $attributes = array();
-    for ($i = 0; $i < $dom_node->attributes->length; $i++) {
-      $attr = $dom_node->attributes->item($i);
+    for ($i = 0; $i < $dom_element->attributes->length; $i++) {
+      $attr = $dom_element->attributes->item($i);
       $attributes[$attr->name] = $attr->value;
     }
 
@@ -205,20 +206,20 @@ protected function prepareImageAttributes($dom_node) {
    *   The UUID for the file.
    * @param string $image_style_id
    *   The ID for the image style.
-   * @param \DOMNode $dom_node
-   *  The DOM node for the image element.
+   * @param \DOMElement $dom_element
+   *  The DOM element for the image element.
    *
    * @return string
    *   The img element with the image style applied.
    */
-  protected function getImageStyleHtml($file_uuid, $image_style_id, \DOMNode $dom_node) {
+  protected function getImageStyleHtml($file_uuid, $image_style_id, \DOMElement $dom_element) {
     $image_info = $this->getImageInfo($file_uuid);
     $image_uri = $image_info['uri'];
     $image_width = $image_info['width'];
     $image_height = $image_info['height'];
 
     // Remove attributes that will be generated by the image style.
-    $attributes = $this->prepareImageAttributes($dom_node);
+    $attributes = $this->prepareImageAttributes($dom_element);
 
     // Re-render as an image style.
     $image = array(
diff --git a/core/modules/image/tests/src/Unit/FilterImageStyleTest.php b/core/modules/image/tests/src/Unit/FilterImageStyleTest.php
index d1f9e4f..3f853f4 100644
--- a/core/modules/image/tests/src/Unit/FilterImageStyleTest.php
+++ b/core/modules/image/tests/src/Unit/FilterImageStyleTest.php
@@ -51,12 +51,11 @@ protected function setUp() {
         $plugin_definition,
         $this->entityTypeManager->reveal(),
         $this->entityRepository->reveal(),
-        $this->imageFactory->reveal(),$this->renderer->reveal()
+        $this->imageFactory->reveal(),
+        $this->renderer->reveal()
       ])
       ->setMethods([
         'loadImageStyles',
-        'getImageInfo',
-        'prepareImageAttributes',
         'getImageStyleHtml'
       ])
       ->getMock();
@@ -79,20 +78,14 @@ public function testProcessWithImage() {
     $original_alt = 'A wooly mammoth trumpets as a crevasse breaks open in the glacier.';
 
     $original_img = '<img src="' . $original_src .'" width="' . $original_width .'" height="' . $original_height .'" alt="' . $original_alt .'" data-entity-uuid="' . $original_uuid . '" data-entity-type="file" data-image-style="' . $original_image_style . '" />';
-    $original_img_doc = new \DOMDocument($original_img);
-    $original_img_node = $original_img_doc->createElement('img');
-
-    $processed_img = '<img alt="' . $original_alt .'" data-entity-type="file" />';
-    $processed_img_doc = new \DOMDocument($processed_img);
-    $processed_img_node = $processed_img_doc->createElement('img');
+    $original_text = '<p>' . $original_img . '</p>';
 
     $generated_src = 'styles/medium/public/image.png';
     $generated_width = '200';
     $generated_height = '150';
 
     $generated_img = '<img src="' . $generated_src .'" width="' . $generated_width .'" height="' . $generated_height .'" alt="' . $original_alt .'" data-entity-type="file" />';
-    $generated_img_doc = new \DOMDocument($generated_img);
-    $generated_img_node = $generated_img_doc->createElement('img');
+    $generated_text = '<p>' . $generated_img . '</p>';
 
     $this->filterImageStyle
       ->method('loadImageStyles')
@@ -103,33 +96,15 @@ public function testProcessWithImage() {
       ]);
 
     $this->filterImageStyle
-      ->method('getImageInfo')
-      ->with(
-        $this->equalTo($original_uuid)
-      )
-      ->willReturn([
-        'uri' => 'styles/medium/public/image.png',
-        'width' => '200',
-        'height'=> '150'
-      ]);
-
-    $this->filterImageStyle
-      ->method('prepareImageAttributes')
-      ->with(
-        $this->equalTo($original_img_node)
-      )
-      ->willReturn($processed_img_node);
-
-    $this->filterImageStyle
       ->method('getImageStyleHtml')
       ->with(
         $this->equalTo($original_uuid),
         $this->equalTo($original_image_style),
-        $this->equalTo($original_img_node)
+        $this->anything()
       )
-      ->willReturn($generated_img_node);
+      ->willReturn($generated_img);
 
-    $output = $this->filterImageStyle->process($original_img, 'en');
-    $this->assertEquals($generated_img_node, $output);
+    $output = $this->filterImageStyle->process($original_text, 'en');
+    $this->assertEquals($generated_text, $output);
   }
 }