diff --git a/mdbook/src/chapter_2/chapter_2_4.md b/mdbook/src/chapter_2/chapter_2_4.md
index 839fc0b8f..4d4289dbf 100644
--- a/mdbook/src/chapter_2/chapter_2_4.md
+++ b/mdbook/src/chapter_2/chapter_2_4.md
@@ -80,7 +80,7 @@ fn main() {
 
             // Acquire a re-activator for this operator.
             use timely::scheduling::Scheduler;
-            let activator = scope.activator_for(&info.address[..]);
+            let activator = scope.activator_for(info.address);
 
             let mut cap = Some(capability);
             move |output| {