diff --git a/lib/easy_lock.h b/lib/easy_lock.h
index 41627c4d48..389b2a56d2 100644
--- a/lib/easy_lock.h
+++ b/lib/easy_lock.h
@@ -18,6 +18,8 @@
  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  * KIND, either express or implied.
  *
+ * SPDX-License-Identifier: curl
+ *
  ***************************************************************************/
 
 #include "curl_setup.h"