diff --git a/core/includes/common.inc b/core/includes/common.inc
index 49cf6e104a..46a7b8fc82 100644
--- a/core/includes/common.inc
+++ b/core/includes/common.inc
@@ -252,19 +252,20 @@ function check_url($uri) {
  */
 function format_size($size, $langcode = NULL) {
   if ($size < Bytes::KILOBYTE) {
-    return \Drupal::translation()->formatPlural($size, '1 byte', '@count bytes', [], ['langcode' => $langcode]);
+    if ($size == -1) {
+      return \Drupal::translation()->t('-1 byte', [], ['langcode' => $langcode]);
+    }
+    else {
+      return \Drupal::translation()->formatPlural($size, '1 byte', '@count bytes', [], ['langcode' => $langcode]);
+    }
   }
   else {
     // Convert bytes to kilobytes.
-    $size = $size / Bytes::KILOBYTE;
-    $units = ['KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'];
-    foreach ($units as $unit) {
-      if (round($size, 2) >= Bytes::KILOBYTE) {
-        $size = $size / Bytes::KILOBYTE;
-      }
-      else {
+    foreach (['B', 'KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'] as $unit) {
+      if (round($size, 2) < Bytes::KILOBYTE) {
         break;
       }
+      $size = $size / Bytes::KILOBYTE;
     }
     $args = ['@size' => round($size, 2)];
     $options = ['langcode' => $langcode];
diff --git a/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php b/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php
index d86ed10bd6..e821cb01fa 100644
--- a/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Common/SizeTest.php
@@ -21,7 +21,7 @@ protected function setUp() {
     $this->exactTestCases = [
       '0 bytes' => 0,
       '1 byte' => 1,
-      '-1 bytes' => -1,
+      '-1 byte' => -1,
       '1 KB'   => $kb,
       '1 MB'   => $kb * $kb,
       '1 GB'   => $kb * $kb * $kb,