[LICENSE] Add SPDX Identifier
diff --git a/utils/ext-def-sky130A.sh b/utils/ext-def-sky130A.sh
index 0977ccf..44cb503 100644
--- a/utils/ext-def-sky130A.sh
+++ b/utils/ext-def-sky130A.sh
@@ -12,6 +12,7 @@
# 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
# To call: ./ext-def-sky130A.sh <target_path> <design_name> <pdk-root> [<output_path> default is <target_path>/results/]
