diff --git a/plot.py b/plot.py
index 412824b..bdf325f 100644
--- a/plot.py
+++ b/plot.py
@@ -1,6 +1,9 @@
 #!/usr/bin/python
 # vim: set fileencoding=utf-8 :
 
+# Copyright (C) Benedikt Bastin, 2021
+# SPDX-License-Identifier: EUPL-1.2
+
 import numpy as np
 import matplotlib.pyplot as plt
 import pandas as pd