diff --git a/docs/running_psalm/issues/PossiblyNullArgument.md b/docs/running_psalm/issues/PossiblyNullArgument.md
index cabaeea33c6..82d3b21d3f5 100644
--- a/docs/running_psalm/issues/PossiblyNullArgument.md
+++ b/docs/running_psalm/issues/PossiblyNullArgument.md
@@ -3,6 +3,8 @@
 Emitted when calling a function with a value that’s possibly null when the function does not expect it
 
 ```php
+<?php
+
 function foo(string $s): void {}
 foo(rand(0, 1) ? "hello" : null);
 ```