diff --git a/docs/library/sys.rst b/docs/library/sys.rst
index aee2e54ee6..d3cc308d89 100644
--- a/docs/library/sys.rst
+++ b/docs/library/sys.rst
@@ -134,3 +134,9 @@ Constants
 .. data:: version_info
 
    Python language version that this implementation conforms to, as a tuple of ints.
+
+    .. admonition:: Difference to CPython
+      :class: attention
+
+      Only the first three version numbers (major, minor, micro) are supported and
+      they can be referenced only by index, not by name.