diff --git a/Doc/lib/liboperator.tex b/Doc/lib/liboperator.tex
index 5ac1b6d063..fbe14f5411 100644
--- a/Doc/lib/liboperator.tex
+++ b/Doc/lib/liboperator.tex
@@ -66,10 +66,12 @@ constructor.
 
 \begin{funcdesc}{is_}{a, b}
 Return \code{\var{a} is \var{b}}.  Tests object identity.
+\versionadded{2.3}
 \end{funcdesc}
 
 \begin{funcdesc}{is_not}{a, b}
 Return \code{\var{a} is not \var{b}}.  Tests object identity.
+\versionadded{2.3}
 \end{funcdesc}