diff --git a/tuos-presentation/beamerthemetuos.sty b/tuos-presentation/beamerthemetuos.sty
index fd4aa87..5936965 100644
--- a/tuos-presentation/beamerthemetuos.sty
+++ b/tuos-presentation/beamerthemetuos.sty
@@ -71,7 +71,7 @@
 \end{frame}
 \egroup}
 
-\newcommand{\ThanksFrame}[1]{%
+\newcommand{\ThanksFrame}[1][]{%
   \begin{frame}[plain]
   \huge
   \begin{center}