diff --git a/slirp/src/debug.h b/slirp/src/debug.h
index 44d922df3708290a2440545b7bc6035fdf861048..2e503ad7fa6b0fb83c76154707f2c3cfba2ee32d 100644
--- a/slirp/src/debug.h
+++ b/slirp/src/debug.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/if.c b/slirp/src/if.c
index 1830cc396c5d5ecbd387348be4ba2f4512f713f2..b8cddebf66796b86f47b85d527df08d74ca776aa 100644
--- a/slirp/src/if.c
+++ b/slirp/src/if.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/if.h b/slirp/src/if.h
index 69569c10df61fbfdec3e66d19cacff3f18bc710c..8a60c4e052b50c968df19d2dcfa39ffa9d1a9675 100644
--- a/slirp/src/if.h
+++ b/slirp/src/if.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/main.h b/slirp/src/main.h
index f11d4572b76b8f8273e8e5ff25a3a30308a87896..a88774215ff4c0a8dcb746935086c5269ad58382 100644
--- a/slirp/src/main.h
+++ b/slirp/src/main.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/mbuf.c b/slirp/src/mbuf.c
index 521c02c96739f4b3c333d9767e9a0874f05fea05..f079a86d7839372aecb507bad6c8559679b40069 100644
--- a/slirp/src/mbuf.c
+++ b/slirp/src/mbuf.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski
  *
diff --git a/slirp/src/misc.c b/slirp/src/misc.c
index 937a418d4ecef363699ee72cae2ac962186abcdc..da41f3bb5f9baa72e6187afdc22e84ede8315751 100644
--- a/slirp/src/misc.c
+++ b/slirp/src/misc.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/misc.h b/slirp/src/misc.h
index c2ceadb591b7a879193cc52e7f42a5fc96f1147d..4eaa2466d736fa8f055f153cf1ddeb1124a968f8 100644
--- a/slirp/src/misc.h
+++ b/slirp/src/misc.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/sbuf.c b/slirp/src/sbuf.c
index 51a9f0cc7d4e5c06ed00fa1cee77aa2e234981ea..815823ffbe4ad2feb04abf97d7610a006216cee7 100644
--- a/slirp/src/sbuf.c
+++ b/slirp/src/sbuf.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/sbuf.h b/slirp/src/sbuf.h
index 1cb9a42834162ce507425fb85142fac600b7c9b9..ece616e3173d0467d1eb24dc35d4120b4b6d65fe 100644
--- a/slirp/src/sbuf.h
+++ b/slirp/src/sbuf.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/socket.c b/slirp/src/socket.c
index f2428a3ae847c2d0b6d62e69a69d973655b19760..ad58262a069fe787b714e4872e9236b99a098f82 100644
--- a/slirp/src/socket.c
+++ b/slirp/src/socket.c
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *
diff --git a/slirp/src/socket.h b/slirp/src/socket.h
index e4d12cd59113b944a2d80215ba13bd8dc7c50d4d..10a0c78a2662609563b79ce10646c65447631593 100644
--- a/slirp/src/socket.h
+++ b/slirp/src/socket.h
@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * Copyright (c) 1995 Danny Gasparovski.
  *