diff --git a/core/includes/file.inc b/core/includes/file.inc
index 5327a38035c..765467fd638 100644
--- a/core/includes/file.inc
+++ b/core/includes/file.inc
@@ -1121,6 +1121,7 @@ function drupal_unlink($uri, $context = NULL) {
  * @see https://www.drupal.org/node/2418133
  */
 function drupal_realpath($uri) {
+  @trigger_error('drupal_realpath() is deprecated in drupal:8.0.0 and will be removed in drupal:9.0.0. Use \Drupal\Core\File\FileSystemInterface::realpath(). See https://www.drupal.org/node/2418133.', E_USER_DEPRECATED);
   return \Drupal::service('file_system')->realpath($uri);
 }
 
diff --git a/core/tests/Drupal/KernelTests/Core/File/FileSystemDeprecationTest.php b/core/tests/Drupal/KernelTests/Core/File/FileSystemDeprecationTest.php
index c70a3e11fb6..58893d1fc47 100644
--- a/core/tests/Drupal/KernelTests/Core/File/FileSystemDeprecationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/File/FileSystemDeprecationTest.php
@@ -252,4 +252,11 @@ class FileSystemDeprecationTest extends KernelTestBase {
     return $data;
   }
 
+  /**
+   * @expectedDeprecation drupal_realpath() is deprecated in drupal:8.0.0 and will be removed in drupal:9.0.0. Use \Drupal\Core\File\FileSystemInterface::realpath(). See https://www.drupal.org/node/2418133.
+   */
+  public function testRealpath() {
+    $this->assertNotEmpty(drupal_realpath('public://'));
+  }
+
 }