diff --git a/docs/library/sys.rst b/docs/library/sys.rst
index c8eb4b5c502b..7b34a0e31c6b 100644
--- a/docs/library/sys.rst
+++ b/docs/library/sys.rst
@@ -69,7 +69,7 @@ Constants
    MicroPython, it has following attributes:
 
    * *name* - string "micropython"
-   * *version* - tuple (major, minor, micro), e.g. (1, 7, 0)
+   * *version* - tuple (major, minor, micro, releaselevel), e.g. (1, 22, 0, '')
    * *_machine* - string describing the underlying machine
    * *_mpy* - supported mpy file-format version (optional attribute)
 
@@ -77,6 +77,9 @@ Constants
    Python implementations (note that it still may not exist in the very
    minimal ports).
 
+   Starting with version 1.22.0-preview, the fourth node *releaselevel* in
+   *implementation.version* is either an empty string or ``"preview"``.
+
    .. admonition:: Difference to CPython
       :class: attention