diff --git a/wtheo.sty b/wtheo.sty
index a02953b..9ab9e63 100644
--- a/wtheo.sty
+++ b/wtheo.sty
@@ -108,6 +108,7 @@
 \DeclareSimpleMathOperator{Cauchy} % Cauchy distribution
 % \DeclareSimpleMathOperator{Normal} % normal distribution
 
+\DeclareSimpleMathOperator{sinc}
 
 \newcommand*\dif{\mathop{}\!\mathrm{d}}
 \newcommand\lecture[3]{\hrule{\color{darkgray}\hfill{\tiny[Lecture #1, #2]}}}