diff --git a/Doc/library/platform.rst b/Doc/library/platform.rst
index 7802422102c..c2b85e6096d 100644
--- a/Doc/library/platform.rst
+++ b/Doc/library/platform.rst
@@ -108,7 +108,7 @@ Cross Platform
 .. function:: python_implementation()
 
    Returns a string identifying the Python implementation. Possible return values
-   are: 'CPython', 'IronPython', 'Jython'.
+   are: 'CPython', 'IronPython', 'Jython', 'PyPy'.
 
    .. versionadded:: 2.6