Fixed typo in documentation.
diff --git a/docs/user/advanced.rst b/docs/user/advanced.rst
index 9d1a94318e..87b180c13b 100644
--- a/docs/user/advanced.rst
+++ b/docs/user/advanced.rst
@@ -124,7 +124,7 @@ will also guarantee execution of the ``response`` hook, described below. ::
 
 .. admonition:: Throttling
 
-    The ``map`` function also takes a ``size`` parameter, that specifies the nubmer of connections to make at a time::
+    The ``map`` function also takes a ``size`` parameter, that specifies the number of connections to make at a time::
 
         async.map(rs, size=5)
 
