diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -5772,7 +5772,7 @@ def update(ui, repo, node=None, rev=None
     current named branch and move the current bookmark (see :hg:`help
     bookmarks`).
 
-    Update sets the working directory's parent revison to the specified
+    Update sets the working directory's parent revision to the specified
     changeset (see :hg:`help parents`).
 
     If the changeset is not a descendant or ancestor of the working