diff --git a/exercises/practice/paasio/src/lib.rs b/exercises/practice/paasio/src/lib.rs
index 8196a6c96..f530460da 100644
--- a/exercises/practice/paasio/src/lib.rs
+++ b/exercises/practice/paasio/src/lib.rs
@@ -1,5 +1,8 @@
 use std::io::{Read, Result, Write};
 
+// the PhantomData instances in this file are just to stop compiler complaints
+// about missing generics; feel free to remove them
+
 pub struct ReadStats<R>(::std::marker::PhantomData<R>);
 
 impl<R: Read> ReadStats<R> {