diff --git a/doc/Using-vipsthumbnail.md b/doc/Using-vipsthumbnail.md
index 52841f52..1ba6e9b3 100644
--- a/doc/Using-vipsthumbnail.md
+++ b/doc/Using-vipsthumbnail.md
@@ -17,8 +17,8 @@ The thumbnailing functionality is implemented by `vips_thumbnail()` and
 see the docs for details. You can use these functions from any language
 with a libvips binding. For example, from PHP you could write:
 
-```php
-$filename = ...;
+```php?start_inline=1 
+$filename = "image.jpg";
 $image = Vips\Image::thumbnail($filename, 200, ["height" => 200]);
 $image->writeToFile("my-thumbnail.jpg");
 ```