diff --git a/tox.ini b/tox.ini
index 0035704..2c85214 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,6 +9,7 @@ deps =
     pytest
     twine
     build
+    matplotlib
 commands =
     check-manifest --ignore 'tox.ini,tests/**,.editorconfig,vscode.env,.vscode/**'
     python -m build