diff -u b/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php b/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php
--- b/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php
+++ b/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php
@@ -28,6 +28,7 @@
    *
    * This function is assigned as an #element_validate callback in
    * fieldSettingsForm().
+   *
    * @param array $element
    *   A field element array.
    * @param \Drupal\Core\Form\FormStateInterface $form_state
@@ -37,7 +38,7 @@
 
     // Spaces are irrelevant to us. Bytes::toInt will process with or without
     // them. Make our lives easier by just doing away with them.
-    self::$size = self::stripSpacesFromString($element['#value']);
+    self::$size = self::stripWhitespaceFromString($element['#value']);
 
     // Having removed whitespace, if our string is now empty then the user
     // either entered nothing or a string of whitespace. Accept both cases as
@@ -77,7 +78,7 @@
    * @return string
    *   Returns the inputted string with spaces removed.
    */
-  private static function stripSpacesFromString($string) {
+  private static function stripWhitespaceFromString($string) {
     return trim(preg_replace('/\s+/', '', $string));
   }