diff --git a/latex/yssymbols.sty b/latex/yssymbols.sty
index 5e12000..aa494a7 100644
--- a/latex/yssymbols.sty
+++ b/latex/yssymbols.sty
@@ -21,6 +21,7 @@
 \def\enstq#1#2{\left\{ #1 \ \middle|\ #2\right\}}
 \def\prive{\setminus}
 \let\vec\overrightarrow
+\DeclareMathOperator{\card}{Card}
 
 \AtBeginDocument{
 \let\leq\leqslant