diff --git a/preambles/packages.tex b/preambles/packages.tex
index b04f6df..664fe95 100644
--- a/preambles/packages.tex
+++ b/preambles/packages.tex
@@ -8,6 +8,7 @@
 
 % Math stuff
 \usepackage{amsmath,amssymb,amsthm}
+\usepackage{mathtools} % extends amsmath
 \usepackage{bbm}
 \usepackage{dsfont} % more blackboard bold symbols like digits and lowercase letters
 \usepackage{bm} % bold math symbols