diff --git a/Doc/lib/libsys.tex b/Doc/lib/libsys.tex
index 7ffa35d..f8f015d 100644
--- a/Doc/lib/libsys.tex
+++ b/Doc/lib/libsys.tex
@@ -31,6 +31,7 @@
   A string representing the Subversion revision that this Python executable
   was built from.  This number is a string because it may contain a trailing
   'M' if Python was built from a mixed revision source tree.
+  \versionadded{2.5}
 \end{datadesc}  
 
 \begin{datadesc}{builtin_module_names}