diff --git a/_pytest/assertion/__init__.py b/_pytest/assertion/__init__.py
index 5bac5b161..91b15bcd5 100644
--- a/_pytest/assertion/__init__.py
+++ b/_pytest/assertion/__init__.py
@@ -25,8 +25,8 @@ def pytest_addoption(parser):
                      help="""control assertion debugging tools.
 'off' performs no assertion debugging.
 'old' reinterprets the expressions in asserts to glean information.
-'new' rewrites the assert statements in test modules to provide sub-expression
-results.""")
+'on' (the default) rewrites the assert statements in test modules to provide
+sub-expression results.""")
     group._addoption('--no-assert', action="store_true", default=False,
         dest="noassert", help="DEPRECATED equivalent to --assertmode=off")
     group._addoption('--nomagic', action="store_true", default=False,