diff --git a/extra/scanlzma/scanlzma.c b/extra/scanlzma/scanlzma.c
index 110f822b..1c8fcd8f 100644
--- a/extra/scanlzma/scanlzma.c
+++ b/extra/scanlzma/scanlzma.c
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
 /*
     scanlzma, scan for lzma compressed data in stdin and echo it to stdout.
     Copyright (C) 2006 Timo Lindfors
diff --git a/lib/Makefile.am b/lib/Makefile.am
index b6a3b161..3309e228 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -1,3 +1,5 @@
+## SPDX-License-Identifier: GPL-2.0-or-later
+
 ##
 ## Copyright (C) 2004-2007 Free Software Foundation, Inc.
 ##
diff --git a/lib/getopt-cdefs.h b/lib/getopt-cdefs.h
index 021bdd36..576428c1 100644
--- a/lib/getopt-cdefs.h
+++ b/lib/getopt-cdefs.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* getopt-on-non-glibc compatibility macros.
    Copyright (C) 1989-2023 Free Software Foundation, Inc.
    This file is part of gnulib.
diff --git a/lib/getopt-core.h b/lib/getopt-core.h
index c5dd4936..126ce808 100644
--- a/lib/getopt-core.h
+++ b/lib/getopt-core.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* Declarations for getopt (basic, portable features only).
    Copyright (C) 1989-2023 Free Software Foundation, Inc.
    This file is part of the GNU C Library and is also part of gnulib.
diff --git a/lib/getopt-ext.h b/lib/getopt-ext.h
index d37c2932..006037ba 100644
--- a/lib/getopt-ext.h
+++ b/lib/getopt-ext.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* Declarations for getopt (GNU extensions).
    Copyright (C) 1989-2023 Free Software Foundation, Inc.
    This file is part of the GNU C Library and is also part of gnulib.
diff --git a/lib/getopt-pfx-core.h b/lib/getopt-pfx-core.h
index 095e3930..ee22d3f7 100644
--- a/lib/getopt-pfx-core.h
+++ b/lib/getopt-pfx-core.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* getopt (basic, portable features) gnulib wrapper header.
    Copyright (C) 1989-2023 Free Software Foundation, Inc.
    This file is part of gnulib.
diff --git a/lib/getopt-pfx-ext.h b/lib/getopt-pfx-ext.h
index 8578d725..00d2a095 100644
--- a/lib/getopt-pfx-ext.h
+++ b/lib/getopt-pfx-ext.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* getopt (GNU extensions) gnulib wrapper header.
    Copyright (C) 1989-2023 Free Software Foundation, Inc.
    This file is part of gnulib.
diff --git a/lib/getopt.c b/lib/getopt.c
index 5941f6fd..ab3ff879 100644
--- a/lib/getopt.c
+++ b/lib/getopt.c
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* Getopt for GNU.
    Copyright (C) 1987-2023 Free Software Foundation, Inc.
    This file is part of the GNU C Library and is also part of gnulib.
diff --git a/lib/getopt.in.h b/lib/getopt.in.h
index 79941d44..6d602c5d 100644
--- a/lib/getopt.in.h
+++ b/lib/getopt.in.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* Declarations for getopt.
    Copyright (C) 1989-2023 Free Software Foundation, Inc.
    This file is part of gnulib.
diff --git a/lib/getopt1.c b/lib/getopt1.c
index fb99b4a0..5cb3b913 100644
--- a/lib/getopt1.c
+++ b/lib/getopt1.c
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* getopt_long and getopt_long_only entry points for GNU getopt.
    Copyright (C) 1987-2023 Free Software Foundation, Inc.
    This file is part of the GNU C Library and is also part of gnulib.
diff --git a/lib/getopt_int.h b/lib/getopt_int.h
index 4d9e24be..2dcb5538 100644
--- a/lib/getopt_int.h
+++ b/lib/getopt_int.h
@@ -1,3 +1,5 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
 /* Internal declarations for getopt.
    Copyright (C) 1989-2023 Free Software Foundation, Inc.
    This file is part of the GNU C Library and is also part of gnulib.
diff --git a/m4/ax_pthread.m4 b/m4/ax_pthread.m4
index 9f35d139..3f26da62 100644
--- a/m4/ax_pthread.m4
+++ b/m4/ax_pthread.m4
@@ -1,3 +1,5 @@
+dnl SPDX-License-Identifier: GPL-3.0-or-later WITH Autoconf-exception-macro
+
 # ===========================================================================
 #        https://www.gnu.org/software/autoconf-archive/ax_pthread.html
 # ===========================================================================
diff --git a/m4/getopt.m4 b/m4/getopt.m4
index 5271f557..af8bfd4c 100644
--- a/m4/getopt.m4
+++ b/m4/getopt.m4
@@ -1,3 +1,5 @@
+dnl SPDX-License-Identifier: FSFULLR
+
 # getopt.m4 serial 49 (modified version)
 dnl Copyright (C) 2002-2006, 2008-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
diff --git a/m4/posix-shell.m4 b/m4/posix-shell.m4
index 4c56193c..95a19a96 100644
--- a/m4/posix-shell.m4
+++ b/m4/posix-shell.m4
@@ -1,3 +1,5 @@
+dnl SPDX-License-Identifier: FSFULLR
+
 # Find a POSIX-conforming shell.
 
 # Copyright (C) 2007-2008 Free Software Foundation, Inc.
diff --git a/m4/visibility.m4 b/m4/visibility.m4
index f0468e89..52c7ef10 100644
--- a/m4/visibility.m4
+++ b/m4/visibility.m4
@@ -1,3 +1,5 @@
+dnl SPDX-License-Identifier: FSFULLR
+
 # visibility.m4 serial 8
 dnl Copyright (C) 2005, 2008, 2010-2023 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
diff --git a/src/scripts/xzdiff.1 b/src/scripts/xzdiff.1
index 24fed680..21824118 100644
--- a/src/scripts/xzdiff.1
+++ b/src/scripts/xzdiff.1
@@ -1,11 +1,10 @@
+.\" SPDX-License-Identifier: GPL-2.0-or-later
 .\"
 .\" Original zdiff.1 for gzip: Jean-loup Gailly
 .\"
 .\" Modifications for XZ Utils: Lasse Collin
 .\"                             Andrew Dudman
 .\"
-.\" License: GNU GPLv2+
-.\"
 .TH XZDIFF 1 "2021-06-04" "Tukaani" "XZ Utils"
 .SH NAME
 xzcmp, xzdiff, lzcmp, lzdiff \- compare compressed files
diff --git a/src/scripts/xzdiff.in b/src/scripts/xzdiff.in
index 72249d3a..40a1fd33 100644
--- a/src/scripts/xzdiff.in
+++ b/src/scripts/xzdiff.in
@@ -1,4 +1,5 @@
 #!@POSIX_SHELL@
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # Copyright (C) 1998, 2002, 2006, 2007 Free Software Foundation
 # Copyright (C) 1993 Jean-loup Gailly
diff --git a/src/scripts/xzgrep.1 b/src/scripts/xzgrep.1
index e0514b8b..0ace8502 100644
--- a/src/scripts/xzgrep.1
+++ b/src/scripts/xzgrep.1
@@ -1,11 +1,10 @@
+.\" SPDX-License-Identifier: GPL-2.0-or-later
 .\"
 .\" Original zgrep.1 for gzip: Jean-loup Gailly
 .\"                            Charles Levert <charles@comm.polymtl.ca>
 .\"
 .\" Modifications for XZ Utils: Lasse Collin
 .\"
-.\" License: GNU GPLv2+
-.\"
 .TH XZGREP 1 "2022-07-19" "Tukaani" "XZ Utils"
 .SH NAME
 xzgrep \- search compressed files for a regular expression
diff --git a/src/scripts/xzgrep.in b/src/scripts/xzgrep.in
index c98fb30d..6e3d8d7e 100644
--- a/src/scripts/xzgrep.in
+++ b/src/scripts/xzgrep.in
@@ -1,4 +1,5 @@
 #!@POSIX_SHELL@
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # xzgrep -- a wrapper around a grep program that decompresses files as needed
 # Adapted from a version sent by Charles Levert <charles@comm.polymtl.ca>
diff --git a/src/scripts/xzless.in b/src/scripts/xzless.in
index 53650ef1..08a64dc7 100644
--- a/src/scripts/xzless.in
+++ b/src/scripts/xzless.in
@@ -1,4 +1,5 @@
 #!@POSIX_SHELL@
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # Copyright (C) 1998, 2002, 2006, 2007 Free Software Foundation
 
diff --git a/src/scripts/xzmore.1 b/src/scripts/xzmore.1
index 9613974e..8a402808 100644
--- a/src/scripts/xzmore.1
+++ b/src/scripts/xzmore.1
@@ -1,9 +1,8 @@
+.\" SPDX-License-Identifier: GPL-2.0-or-later
 .\"
 .\" Original zdiff.1 for gzip: Jean-loup Gailly
 .\" Modifications for XZ Utils: Lasse Collin
 .\"
-.\" License: GNU GPLv2+
-.\"
 .TH XZMORE 1 "2013-06-30" "Tukaani" "XZ Utils"
 .SH NAME
 xzmore, lzmore \- view xz or lzma compressed (text) files
diff --git a/src/scripts/xzmore.in b/src/scripts/xzmore.in
index 5188fdab..7cb31cbe 100644
--- a/src/scripts/xzmore.in
+++ b/src/scripts/xzmore.in
@@ -1,4 +1,5 @@
 #!@POSIX_SHELL@
+# SPDX-License-Identifier: GPL-2.0-or-later
 
 # Copyright (C) 2001, 2002, 2007 Free Software Foundation
 # Copyright (C) 1992, 1993 Jean-loup Gailly