diff --git a/slirp/src/dhcpv6.h b/slirp/src/dhcpv6.h
index af0e193b06..dc26a93cff 100644
--- a/slirp/src/dhcpv6.h
+++ b/slirp/src/dhcpv6.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Definitions and prototypes for SLIRP stateless DHCPv6
  *
diff --git a/slirp/src/ip.h b/slirp/src/ip.h
index 73a4d2a3d2..1484de1176 100644
--- a/slirp/src/ip.h
+++ b/slirp/src/ip.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/ip_icmp.h b/slirp/src/ip_icmp.h
index a4e5b8b265..05d85c59dd 100644
--- a/slirp/src/ip_icmp.h
+++ b/slirp/src/ip_icmp.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/mbuf.h b/slirp/src/mbuf.h
index e2d443418a..732c85c63c 100644
--- a/slirp/src/mbuf.h
+++ b/slirp/src/mbuf.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/ncsi-pkt.h b/slirp/src/ncsi-pkt.h
index 3867feb1d3..4c0be39f6e 100644
--- a/slirp/src/ncsi-pkt.h
+++ b/slirp/src/ncsi-pkt.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright Gavin Shan, IBM Corporation 2016.
  *
diff --git a/slirp/src/qtailq.h b/slirp/src/qtailq.h
index a89b0c439a..d8aa0e19a4 100644
--- a/slirp/src/qtailq.h
+++ b/slirp/src/qtailq.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*      $NetBSD: queue.h,v 1.52 2009/04/20 09:56:08 mschuett Exp $ */
 
 /*
diff --git a/slirp/src/tcp.h b/slirp/src/tcp.h
index 47aaea6c5b..79d3251bb5 100644
--- a/slirp/src/tcp.h
+++ b/slirp/src/tcp.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/tcp_timer.h b/slirp/src/tcp_timer.h
index b25b3911d7..709f63987a 100644
--- a/slirp/src/tcp_timer.h
+++ b/slirp/src/tcp_timer.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/tcp_var.h b/slirp/src/tcp_var.h
index 27ef1a51cb..162be6e95e 100644
--- a/slirp/src/tcp_var.h
+++ b/slirp/src/tcp_var.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1993, 1994
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/tcpip.h b/slirp/src/tcpip.h
index 07dbf2c432..560a86417c 100644
--- a/slirp/src/tcpip.h
+++ b/slirp/src/tcpip.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/udp.h b/slirp/src/udp.h
index 3d29504caa..29c0297179 100644
--- a/slirp/src/udp.h
+++ b/slirp/src/udp.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/vmstate.h b/slirp/src/vmstate.h
index 21157b5ec2..44efea7b50 100644
--- a/slirp/src/vmstate.h
+++ b/slirp/src/vmstate.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * QEMU migration/snapshot declarations
  *
diff --git a/slirp/src/cksum.c b/slirp/src/cksum.c
index 25bfa67348..9599f6a280 100644
--- a/slirp/src/cksum.c
+++ b/slirp/src/cksum.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1988, 1992, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/dhcpv6.c b/slirp/src/dhcpv6.c
index df350e9f26..3c8f420912 100644
--- a/slirp/src/dhcpv6.c
+++ b/slirp/src/dhcpv6.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * SLIRP stateless DHCPv6
  *
diff --git a/slirp/src/ip_icmp.c b/slirp/src/ip_icmp.c
index 120108f582..1aea18afa7 100644
--- a/slirp/src/ip_icmp.c
+++ b/slirp/src/ip_icmp.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/ip_input.c b/slirp/src/ip_input.c
index e0b94b0e42..6ad6765938 100644
--- a/slirp/src/ip_input.c
+++ b/slirp/src/ip_input.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/ip_output.c b/slirp/src/ip_output.c
index f6ec141df5..9299997efb 100644
--- a/slirp/src/ip_output.c
+++ b/slirp/src/ip_output.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/ncsi.c b/slirp/src/ncsi.c
index 1169da8241..6d574ec5ec 100644
--- a/slirp/src/ncsi.c
+++ b/slirp/src/ncsi.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * NC-SI (Network Controller Sideband Interface) "echo" model
  *
diff --git a/slirp/src/tcp_input.c b/slirp/src/tcp_input.c
index b10477fc57..cf54eeee92 100644
--- a/slirp/src/tcp_input.c
+++ b/slirp/src/tcp_input.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/tcp_output.c b/slirp/src/tcp_output.c
index e9674df121..272c261d07 100644
--- a/slirp/src/tcp_output.c
+++ b/slirp/src/tcp_output.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c
index 1db59caa89..086e4e98e2 100644
--- a/slirp/src/tcp_subr.c
+++ b/slirp/src/tcp_subr.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/tcp_timer.c b/slirp/src/tcp_timer.c
index 7be54570af..be361a1bb6 100644
--- a/slirp/src/tcp_timer.c
+++ b/slirp/src/tcp_timer.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/udp.c b/slirp/src/udp.c
index fa9f4a08bd..27bb829c37 100644
--- a/slirp/src/udp.c
+++ b/slirp/src/udp.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1982, 1986, 1988, 1990, 1993
  *	The Regents of the University of California.  All rights reserved.
diff --git a/slirp/src/vmstate.c b/slirp/src/vmstate.c
index 3bc23d1d73..43bb3ebc6f 100644
--- a/slirp/src/vmstate.c
+++ b/slirp/src/vmstate.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * VMState interpreter
  *
