diff --git a/core/modules/file/file.module b/core/modules/file/file.module
index 76e199f..368a80c 100644
--- a/core/modules/file/file.module
+++ b/core/modules/file/file.module
@@ -5,6 +5,7 @@
  * Defines a "managed_file" Form API field and a "file" field for Field module.
  */
 
+use Drupal\file\FileInterface;
 use Drupal\file\Entity\File;
 use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Entity\EntityStorageControllerInterface;
@@ -424,7 +425,7 @@ function file_validate_is_image(File $file) {
  * Non-image files will be ignored. If an image toolkit is available, the image
  * will be scaled to fit within the desired maximum dimensions.
  *
- * @param Drupal\file\Entity\File $file
+ * @param \Drupal\file\FileInterface $file
  *   A file entity. This function may resize the file affecting its size.
  * @param string $maximum_dimensions
  *   An optional string in the form WIDTHxHEIGHT e.g. '640x480' or '85x85'. If
@@ -440,13 +441,13 @@ function file_validate_is_image(File $file) {
  *
  * @see hook_file_validate()
  */
-function file_validate_image_dimensions(File $file, $maximum_dimensions = '', $minimum_dimensions = '') {
+function file_validate_image_dimensions(FileInterface $file, $maximum_dimensions = '', $minimum_dimensions = '') {
   $errors = array();
 
-  // Check first that the file is an image.
-  /** @var $image_factory Drupal\Core\Image\ImageFactory */
+  /** @var $image_factory \Drupal\Core\Image\ImageFactory */
   $image_factory = \Drupal::service('image.factory');
   $image = $image_factory->get($file->getFileUri());
+  // First check that the file is an image.
   if ($image->getExtension()) {
     if ($maximum_dimensions) {
       // Check that it is smaller than the given dimensions.
@@ -460,15 +461,15 @@ function file_validate_image_dimensions(File $file, $maximum_dimensions = '', $m
               drupal_set_message(t('The image was resized to fit within the maximum allowed dimensions of %dimensions pixels.', array('%dimensions' => $maximum_dimensions)));
             }
             else {
-              $errors[] = t('The image is too large and saving a resized version failed.');
+              $errors[] = t('The image exceeds the maximum allowed dimensions and saving a resized version failed.');
             }
           }
           else {
-            $errors[] = t('The image is too large but resizing failed.');
+            $errors[] = t('The image exceeds the maximum allowed dimensions and resizing it failed.');
           }
         }
         else {
-          $errors[] = t('The image is too large; the maximum dimensions are %dimensions pixels.', array('%dimensions' => $maximum_dimensions));
+          $errors[] = t('The image exceeds the maximum allowed dimensions of %dimensions pixels.', array('%dimensions' => $maximum_dimensions));
         }
       }
     }
@@ -787,7 +788,7 @@ function file_save_upload($form_field_name, $validators = array(), $destination
   $uploaded_files = $_FILES;
   if (!is_array($uploaded_files['files']['name'][$form_field_name])) {
     foreach (array('name', 'type', 'tmp_name', 'error', 'size') as $value)
-    $uploaded_files['files'][$value][$form_field_name] = array($uploaded_files['files'][$value][$form_field_name]);
+      $uploaded_files['files'][$value][$form_field_name] = array($uploaded_files['files'][$value][$form_field_name]);
   }
 
   $files = array();
@@ -815,7 +816,7 @@ function file_save_upload($form_field_name, $validators = array(), $destination
           break;
         }
 
-        // Unknown error
+      // Unknown error
       default:
         drupal_set_message(t('The file %file could not be saved. An unknown error has occurred.', array('%file' => $name)), 'error');
         $files[$i] = FALSE;