diff --git a/src/util/makeutils.py b/src/util/makeutils.py
index da47cd2..aad2d80 100644
--- a/src/util/makeutils.py
+++ b/src/util/makeutils.py
@@ -166,7 +166,7 @@ def collect_latex_packages(
         )
 
     if add_matplotlib_deps:
-        deps.add("type1cm")
+        deps.update(["type1cm", "underscore"])
 
     packages = set()
     for dep in deps:
diff --git a/tl_packages.txt b/tl_packages.txt
index 9d2d69f..fe526fd 100644
--- a/tl_packages.txt
+++ b/tl_packages.txt
@@ -66,6 +66,7 @@ standalone
 tipa
 tools
 type1cm
+underscore
 uniquecounter
 url
 wasy