diff --git a/ptbposter/ptbposter.cls b/ptbposter/ptbposter.cls
index 8508378a54897448ef48b24a3c3cd2e7656d4c0d..0de47b3d6547b2d8b6c620f61d4920f145523e76 100644
--- a/ptbposter/ptbposter.cls
+++ b/ptbposter/ptbposter.cls
@@ -330,7 +330,10 @@
   \PTBlandscapetrue
 \fi
 
-\RequirePackage{relsize}\renewcommand\RSpercentTolerance{0}% ???
+\RequirePackage{relsize}% ???
+\renewcommand*\RSpercentTolerance{0}% 
+\renewcommand*\RSlargest{1000pt}% important!
+\renewcommand*\RSsmallest{0pt}
 
 \newcommand*\scaleFontSizes[1]{%
   \global\PTB@default@fsize=#1\PTB@default@fontsize@base