diff --git a/gds/.gitignore b/gds/.gitignore
index baf330a..a0c9f17 100644
--- a/gds/.gitignore
+++ b/gds/.gitignore
@@ -1 +1,2 @@
 *.gds
+tmp/
\ No newline at end of file
diff --git a/gds/drc_on_gds.tcl b/gds/drc_on_gds.tcl
index f82822b..8bb3035 100644
--- a/gds/drc_on_gds.tcl
+++ b/gds/drc_on_gds.tcl
@@ -1,3 +1,18 @@
+# SPDX-FileCopyrightText: 2020 Efabless Corporation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# SPDX-License-Identifier: Apache-2.0
+
 gds read $::env(DESIGN_IN_DRC).gds
 set fout [open ./tmp/$::env(DESIGN_IN_DRC).drc w]
 set oscale [cif scale out]