diff --git a/docs/serving/samples/hello-world/helloworld-php/README.md b/docs/serving/samples/hello-world/helloworld-php/README.md
index 943f1ca9f..bd53a8883 100644
--- a/docs/serving/samples/hello-world/helloworld-php/README.md
+++ b/docs/serving/samples/hello-world/helloworld-php/README.md
@@ -28,7 +28,7 @@ recreate the source files from this folder.
    ```php
    <?php
    $target = getenv('TARGET', true) ?: 'World';
-   echo sprintf('Hello %s!', $target);
+   echo sprintf("Hello %s!", $target);
    ```
 
 1. Create a file named `Dockerfile` and copy the code block below into it. See
diff --git a/docs/serving/samples/hello-world/helloworld-php/index.php b/docs/serving/samples/hello-world/helloworld-php/index.php
index 1dfe9b3c6..4107bec64 100644
--- a/docs/serving/samples/hello-world/helloworld-php/index.php
+++ b/docs/serving/samples/hello-world/helloworld-php/index.php
@@ -1,3 +1,3 @@
 <?php
 $target = getenv('TARGET', true) ?: 'World';
-echo sprintf('Hello %s!', $target);
+echo sprintf("Hello %s!", $target);