diff --git a/base64.c b/base64.c
index 663763e..30aaca7 100644
--- a/base64.c
+++ b/base64.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 1995-2001 Kungliga Tekniska Högskolan
  * (Royal Institute of Technology, Stockholm, Sweden).
  * All rights reserved.
diff --git a/conf.c b/conf.c
index 84b574b..aafe7e3 100644
--- a/conf.c
+++ b/conf.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
  * This code is derived from software contributed to The DragonFly Project
diff --git a/crypto.c b/crypto.c
index 94d96d0..37c3e4a 100644
--- a/crypto.c
+++ b/crypto.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
  * This code is derived from software contributed to The DragonFly Project
diff --git a/dfcompat.c b/dfcompat.c
index d4ecc1d..b9e87cc 100644
--- a/dfcompat.c
+++ b/dfcompat.c
@@ -1,6 +1,7 @@
 #ifndef HAVE_STRLCPY
-
 /*
+ * SPDX-License-Identifier: BSD-2-Clause AND ISC
+ *
  * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
  *
  * Permission to use, copy, modify, and distribute this software for any
diff --git a/dma-mbox-create.c b/dma-mbox-create.c
index 37011e0..5f45f0a 100644
--- a/dma-mbox-create.c
+++ b/dma-mbox-create.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2010-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/dma.c b/dma.c
index 35b9b48..d09f5f2 100644
--- a/dma.c
+++ b/dma.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/dma.h b/dma.h
index 41588eb..d498017 100644
--- a/dma.h
+++ b/dma.h
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/dns.c b/dns.c
index 8867c83..e76e2a8 100644
--- a/dns.c
+++ b/dns.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/local.c b/local.c
index 0b5030d..dbaccfa 100644
--- a/local.c
+++ b/local.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/mail.c b/mail.c
index e3057d9..90a49d0 100644
--- a/mail.c
+++ b/mail.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/net.c b/net.c
index 81b304b..320ba5a 100644
--- a/net.c
+++ b/net.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/spool.c b/spool.c
index 81812f1..7ec4983 100644
--- a/spool.c
+++ b/spool.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *
diff --git a/util.c b/util.c
index 4679184..6d8d63b 100644
--- a/util.c
+++ b/util.c
@@ -1,4 +1,6 @@
 /*
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
  * Copyright (c) 2008-2014, Simon Schubert <2@0x2c.org>.
  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
  *