diff --git a/tex/preamble.tex b/tex/preamble.tex
index 27b5f3b..2471c54 100644
--- a/tex/preamble.tex
+++ b/tex/preamble.tex
@@ -4,6 +4,9 @@
 % Enable captions for figures and tables.
 \usepackage{caption}
 
+% Enable math formulae.
+\usepackage{amsmath}
+
 % Enable diagonal lines in tables.
 \usepackage{static/slashbox}