diff --git a/README.md b/README.md
index 767622e..60ca976 100644
--- a/README.md
+++ b/README.md
@@ -16,6 +16,10 @@ First, install Tampermonkey. Then, visit the [installation website](https://holl
 
 It fills in the `@match` directives for whatever instances are relevant to the user, using GET parameters so Tampermonkey's update functionality will continue to work.
 
+### Why is there PHP in a .user.js file?
+
+For the same reason as the last question. That's how the `@match` directives are filled in with the GET parameters. The file has to have the .user.js extension so that Tampermonkey will prompt the user to install it, which means I had to go into the PHP configuration files and allow it to execute .js files as PHP. It's a little cursed but it does work.
+
 ## TODO
 
 - Figure out why it doesn't work on Firefox