diff --git a/src/libcore/iter/mod.rs b/src/libcore/iter/mod.rs
index d9b8c5ea589..df4aef08871 100644
--- a/src/libcore/iter/mod.rs
+++ b/src/libcore/iter/mod.rs
@@ -336,7 +336,7 @@ mod range;
 mod sources;
 mod traits;
 
-/// An double-ended iterator with the direction inverted.
+/// A double-ended iterator with the direction inverted.
 ///
 /// This `struct` is created by the [`rev()`] method on [`Iterator`]. See its
 /// documentation for more.