diff --git a/beamertheme/beamerthemeOSAK.sty b/beamertheme/beamerthemeOSAK.sty
index cb17eb542f6d6aaf98a80a2222f5ae4d8517c611..6347f71674b8ac9cbfcda901c896415738785d01 100644
--- a/beamertheme/beamerthemeOSAK.sty
+++ b/beamertheme/beamerthemeOSAK.sty
@@ -20,6 +20,9 @@
 \setbeamercolor{section number projected}{bg=darkred!80!gray}
 \setbeamertemplate{subsection in toc}[square]
 \setbeamercolor{subsection number projected}{bg=darkred!80!gray}
+\setbeamercolor{alerted text}{fg=red!90!black}
+\setbeamercolor{block title alerted}{bg=darkred, fg=white}
+\setbeamercolor{block body alerted}{bg=red!12!white}
 \beamertemplatenavigationsymbolsempty
 
 \logo{\includegraphics[height=2cm]{osak-logo}}