2.7 -> 3.1 versionchanges.
diff --git a/Doc/library/test.rst b/Doc/library/test.rst
index 2da63ac..353715b 100644
--- a/Doc/library/test.rst
+++ b/Doc/library/test.rst
@@ -389,7 +389,7 @@
    manager all changes to environment variables done through this instance will
    be rolled back.
 
-   .. versionchanged:: 2.7
+   .. versionchanged:: 3.1
       Added dictionary interface.
 
 .. method:: EnvironmentVarGuard.set(envvar, value)