diff --git a/envs/environment.fixed.yaml b/envs/environment.fixed.yaml
index 8e7bb9780..558db60e9 100644
--- a/envs/environment.fixed.yaml
+++ b/envs/environment.fixed.yaml
@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: : 2017-2020 The PyPSA-Eur Authors
+#
+# SPDX-License-Identifier: GPL-3.0-or-later
+
 name: pypsa-eur
 channels:
   - bioconda