diff --git a/ncsid/src/normalize_ip.c b/ncsid/src/normalize_ip.c
index 107d29f..77783cc 100644
--- a/ncsid/src/normalize_ip.c
+++ b/ncsid/src/normalize_ip.c
@@ -1,3 +1,19 @@
+/*
+ * Copyright 2021 Google LLC
+ *
+ * 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.
+ */
+
 #include <arpa/inet.h>
 #include <stdio.h>