diff --git a/examples/generate_phpdoc.py b/examples/generate_phpdoc.py
index 9676c8e..0f2c60f 100755
--- a/examples/generate_phpdoc.py
+++ b/examples/generate_phpdoc.py
@@ -265,6 +265,8 @@ def add_nickname(gtype, a, b):
         f.write(' */\n')
         f.write('abstract class ImageAutodoc extends VipsObject\n')
         f.write('{\n')
+        f.write('    abstract public function __set(string $name, $value);\n')
+        f.write('    abstract public function __get(string $name);\n')
         f.write('}\n')
 
 
diff --git a/src/ImageAutodoc.php b/src/ImageAutodoc.php
index 531084a..529c834 100644
--- a/src/ImageAutodoc.php
+++ b/src/ImageAutodoc.php
@@ -703,4 +703,6 @@
  */
 abstract class ImageAutodoc extends VipsObject
 {
+    abstract public function __set(string $name, $value);
+    abstract public function __get(string $name);
 }