diff --git a/docs/iris.sty b/docs/iris.sty
index 0b5ca1b607b9c62c75df5e2d3933a361aad74250..73b727b20d0248caad5b24dc876f4967488f9455 100644
--- a/docs/iris.sty
+++ b/docs/iris.sty
@@ -145,7 +145,7 @@
 \newcommand{\mcar}[1]{|#1|}
 \newcommand{\mcarp}[1]{\mcar{#1}^{+}}
 \newcommand{\munit}{\varepsilon}
-\newcommand{\mcore}[1]{\lfloor#1\rfloor}
+\newcommand{\mcore}[1]{\llparenthesis#1\rrparenthesis}
 \newcommand{\mtimes}{\mathbin{\cdot}}
 
 \newcommand{\mupd}{\rightsquigarrow}