diff --git a/preface.tex b/preface.tex
index b5c8169..1bdf64f 100644
--- a/preface.tex
+++ b/preface.tex
@@ -28,6 +28,6 @@ You can always send feedback on the book to
 \texttt{ahslaaks@cs.helsinki.fi}.
 
 \begin{flushright}
-Helsinki, February 2017 \\
+Helsinki, March 2017 \\
 Antti Laaksonen
-\end{flushright}
\ No newline at end of file
+\end{flushright}