diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index 5ec71b7353c3e..84fe5ba1fbf5a 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -11,7 +11,8 @@
 //! A growable list type with heap-allocated contents, written `Vec<T>` but
 //! pronounced 'vector.'
 //!
-//! Vectors have `O(1)` indexing, push (to the end) and pop (from the end).
+//! Vectors have `O(1)` indexing, amortized `O(1)` push (to the end) and
+//! `O(1)` pop (from the end).
 //!
 //! # Examples
 //!