diff --git a/CELbeamer.cls b/CELbeamer.cls
index a566e89..bb63196 100644
--- a/CELbeamer.cls
+++ b/CELbeamer.cls
@@ -117,6 +117,7 @@
 \RequirePackage[scaled=.92]{beramono}
 \RequirePackage{libertineRoman}
 \RequirePackage{lmodern}
+\RequirePackage{exscale} % Correct scaling of \sum, \prod, \int, and the likes
 % Semibold
 \DeclareRobustCommand{\sbseries}{\fontseries{sb}\selectfont}
 \DeclareTextFontCommand{\textsb}{\sbseries}
@@ -1361,4 +1362,4 @@
 \newcommand{\backupend}{
    \addtocounter{framenumbervorappendix}{-\value{framenumber}}
    \addtocounter{framenumber}{\value{framenumbervorappendix}} 
-}
\ No newline at end of file
+}