diff --git a/core/lib/Drupal/Component/PhpStorage/MTimeProtectedFastFileStorage.php b/core/lib/Drupal/Component/PhpStorage/MTimeProtectedFastFileStorage.php
index 3c5d55d..c7e6feb 100644
--- a/core/lib/Drupal/Component/PhpStorage/MTimeProtectedFastFileStorage.php
+++ b/core/lib/Drupal/Component/PhpStorage/MTimeProtectedFastFileStorage.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Component\PhpStorage;
 
+use Drupal\Component\Utility\Crypt;
+
 /**
  * Stores PHP code in files with securely hashed names.
  *
@@ -130,7 +132,7 @@ public function getFullPath($name, &$directory = NULL, &$directory_mtime = NULL)
     if (!isset($directory_mtime)) {
       $directory_mtime = file_exists($directory) ? filemtime($directory) : 0;
     }
-    return $directory . '/' . hash_hmac('sha256', $name, $this->secret . $directory_mtime) . '.php';
+    return $directory . '/' . Crypt::hmacBase64($name, $this->secret . $directory_mtime) . '.php';
   }
 
   /**
@@ -225,7 +227,7 @@ protected function getUncachedMTime($directory) {
    */
   protected function tempnam($directory, $prefix) {
     do {
-      $path = $directory . '/' . $prefix . substr(str_shuffle(hash('sha256', microtime())), 0, 10);
+      $path = $directory . '/' . $prefix . Crypt::randomBytesBase64(20);
     } while (file_exists($path));
     return $path;
   }
diff --git a/core/tests/Drupal/Tests/Component/PhpStorage/MTimeProtectedFileStorageBase.php b/core/tests/Drupal/Tests/Component/PhpStorage/MTimeProtectedFileStorageBase.php
index 64d17eb..af9fa05 100644
--- a/core/tests/Drupal/Tests/Component/PhpStorage/MTimeProtectedFileStorageBase.php
+++ b/core/tests/Drupal/Tests/Component/PhpStorage/MTimeProtectedFileStorageBase.php
@@ -2,6 +2,8 @@
 
 namespace Drupal\Tests\Component\PhpStorage;
 
+use Drupal\Component\Utility\Crypt;
+
 /**
  * Base test class for MTime protected storage.
  */
@@ -77,7 +79,7 @@ public function testSecurity() {
       $expected_directory = $expected_root_directory . '/' . $name;
     }
     $directory_mtime = filemtime($expected_directory);
-    $expected_filename = $expected_directory . '/' . hash_hmac('sha256', $name, $this->secret . $directory_mtime) . '.php';
+    $expected_filename = $expected_directory . '/' . Crypt::hmacBase64($name, $this->secret . $directory_mtime) . '.php';
 
     // Ensure the file exists and that it and the containing directory have
     // minimal permissions. fileperms() can return high bits unrelated to