diff --git a/Doc/lib/libtime.tex b/Doc/lib/libtime.tex
index 2e9de609ce8..d28e8638eef 100644
--- a/Doc/lib/libtime.tex
+++ b/Doc/lib/libtime.tex
@@ -173,7 +173,8 @@ is the full 9-tuple (since the dst flag is needed; use \code{-1} as
 the dst flag if it is unknown) which expresses the time in
 \emph{local} time, not UTC.  It returns a floating point number, for
 compatibility with \function{time()}.  If the input value cannot be
-represented as a valid time, \exception{OverflowError} is raised.
+represented as a valid time, \exception{OverflowError} is raised.  The
+earliest date for which it can generate a time is platform-dependent.
 \end{funcdesc}
 
 \begin{funcdesc}{sleep}{secs}