diff --git a/mercurial/rewriteutil.py b/mercurial/rewriteutil.py
--- a/mercurial/rewriteutil.py
+++ b/mercurial/rewriteutil.py
@@ -34,7 +34,7 @@
     Make sure this function is called after taking the lock.
     """
     if nullrev in revs:
-        msg = _(b"cannot %s null changeset") % action
+        msg = _(b"cannot %s the null revision") % action
         hint = _(b"no changeset checked out")
         raise error.InputError(msg, hint=hint)
 
diff --git a/tests/test-uncommit.t b/tests/test-uncommit.t
--- a/tests/test-uncommit.t
+++ b/tests/test-uncommit.t
@@ -51,7 +51,7 @@
 Uncommit with no commits should fail
 
   $ hg uncommit
-  abort: cannot uncommit null changeset
+  abort: cannot uncommit the null revision
   (no changeset checked out)
   [10]