diff --git a/core/modules/file/src/Plugin/Field/FieldType/FileItem.php b/core/modules/file/src/Plugin/Field/FieldType/FileItem.php
index 9307667..0ef2d61 100644
--- a/core/modules/file/src/Plugin/Field/FieldType/FileItem.php
+++ b/core/modules/file/src/Plugin/Field/FieldType/FileItem.php
@@ -251,8 +251,8 @@ public static function validateExtensions($element, FormStateInterface $form_sta
    * fieldSettingsForm().
    */
   public static function validateMaxFilesize($element, FormStateInterface $form_state) {
-    if (!empty($element['#value']) && !is_numeric(Bytes::toInt($element['#value']))) {
-      $form_state->setError($element, t('The "!name" option must contain a valid value. You may either leave the text field empty or enter a string like "512" (bytes), "80 KB" (kilobytes) or "50 MB" (megabytes).', array('!name' => t($element['title']))));
+    if (!empty($element['#value']) && !Bytes::toInt($element['#value'])) {
+      $form_state->setError($element, t('The "!name" option must contain a valid value. You may either leave the text field empty or enter a string like "512" (bytes), "80 KB" (kilobytes) or "50 MB" (megabytes).', array('!name' => t($element['#title']))));
     }
   }