diff --git a/src/libcore/iter/iterator.rs b/src/libcore/iter/iterator.rs
index c0681619bf8b5..afc273d265b9c 100644
--- a/src/libcore/iter/iterator.rs
+++ b/src/libcore/iter/iterator.rs
@@ -384,7 +384,9 @@ pub trait Iterator {
     ///
     /// In other words, it zips two iterators together, into a single one.
     ///
-    /// If either iterator returns [`None`], [`next`] will return [`None`].
+    /// If either iterator returns [`None`], [`next`] from the zipped iterator
+    /// will return [`None`]. If the first iterator returns [`None`], `zip` will
+    /// short-circuit and `next` will not be called on the second iterator.
     ///
     /// # Examples
     ///