diff --git a/Makefile.am b/Makefile.am
index 22b4fa3..56279c4 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,4 +1,4 @@
-
+# SPDX-License-Identifier: GPL-2.0
 AM_MAKEFLAGS = --no-print-directory
 AM_CPPFLAGS =
 
diff --git a/Makefile.mesh b/Makefile.mesh
index 10573b3..228dd1b 100644
--- a/Makefile.mesh
+++ b/Makefile.mesh
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 if MESH
 
 if DATAFILES
diff --git a/Makefile.obexd b/Makefile.obexd
index de59d29..6f5dc04 100644
--- a/Makefile.obexd
+++ b/Makefile.obexd
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 if SYSTEMD
 systemduserunitdir = $(SYSTEMD_USERUNITDIR)
 systemduserunit_DATA = obexd/src/obex.service
diff --git a/Makefile.plugins b/Makefile.plugins
index 98eee9e..3b673bf 100644
--- a/Makefile.plugins
+++ b/Makefile.plugins
@@ -1,4 +1,4 @@
-
+# SPDX-License-Identifier: GPL-2.0
 builtin_modules += hostname
 builtin_sources += plugins/hostname.c
 
diff --git a/Makefile.tools b/Makefile.tools
index e260a7f..0423293 100644
--- a/Makefile.tools
+++ b/Makefile.tools
@@ -1,4 +1,4 @@
-
+# SPDX-License-Identifier: GPL-2.0
 if CLIENT
 bin_PROGRAMS += client/bluetoothctl
 
diff --git a/configure.ac b/configure.ac
index 292dca6..d6347c0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 AC_PREREQ(2.60)
 AC_INIT(bluez, 5.55)