diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
index 355266c..eb12aa7 100644
--- a/Doc/lib/libstdtypes.tex
+++ b/Doc/lib/libstdtypes.tex
@@ -723,6 +723,7 @@
 Return the numeric string left filled with zeros in a string
 of length \var{width}. The original string is returned if
 \var{width} is less than \code{len(\var{s})}.
+\versionadded{2.2.2}
 \end{methoddesc}