diff --git a/core/lib/Drupal/Component/Yaml/Yaml.php b/core/lib/Drupal/Component/Yaml/Yaml.php
index a632416..4272618 100644
--- a/core/lib/Drupal/Component/Yaml/Yaml.php
+++ b/core/lib/Drupal/Component/Yaml/Yaml.php
@@ -72,7 +72,7 @@ protected function determineImplementation() {
       static::$implementationClass = $class;
     }
     // If the PECL YAML extension installed, use that.
-    elseif (function_exists('yaml_emit')) {
+    elseif (extension_loaded('yaml_emit')) {
       static::$implementationClass = 'Drupal\Component\Yaml\Pecl';
     }
     else {
diff --git a/core/tests/Drupal/Tests/Component/Yaml/YamlTest.php b/core/tests/Drupal/Tests/Component/Yaml/YamlTest.php
index b0af7f9..7129a73 100644
--- a/core/tests/Drupal/Tests/Component/Yaml/YamlTest.php
+++ b/core/tests/Drupal/Tests/Component/Yaml/YamlTest.php
@@ -29,9 +29,7 @@ public static function getInfo() {
 
   protected function setUp() {
     if (!extension_loaded('yaml')) {
-      $this->markTestSkipped(
-           'The PECL Yaml extension is not available.'
-      );
+      $this->markTestSkipped('The PECL Yaml extension is not available.');
     }
   }