diff --git a/src/libcore/iter/traits/iterator.rs b/src/libcore/iter/traits/iterator.rs
index 7ffc8b3729cb4..b7a35568e3fc5 100644
--- a/src/libcore/iter/traits/iterator.rs
+++ b/src/libcore/iter/traits/iterator.rs
@@ -201,12 +201,13 @@ pub trait Iterator {
 
     /// Consumes the iterator, counting the number of iterations and returning it.
     ///
-    /// This method will evaluate the iterator until its [`next`] returns
-    /// [`None`]. Once [`None`] is encountered, `count()` returns the number of
-    /// times it called [`next`].
+    /// This method will call [`next`] repeatedly until [`None`] is encountered,
+    /// returning the number of times it saw [`Some`]. Note that [`next`] has to be
+    /// called at least once even if the iterator does not have any elements.
     ///
     /// [`next`]: #tymethod.next
     /// [`None`]: ../../std/option/enum.Option.html#variant.None
+    /// [`Some`]: ../../std/option/enum.Option.html#variant.Some
     ///
     /// # Overflow Behavior
     ///