diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 5b76900f44..da7762b450 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,3 +1,5 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
 add_subdirectory(Build)
 add_subdirectory(3rdParty)
 add_subdirectory(Base)
diff --git a/src/FCConfig.h b/src/FCConfig.h
index 294d16ad4c..6b669d6b9d 100644
--- a/src/FCConfig.h
+++ b/src/FCConfig.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
 /***************************************************************************
  *   Copyright (c) 2004 Jürgen Riegel <juergen.riegel@web.de>              *
  *                                                                         *
diff --git a/src/FCGlobal.h b/src/FCGlobal.h
index db3034e39b..b69ea786da 100644
--- a/src/FCGlobal.h
+++ b/src/FCGlobal.h
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
 /***************************************************************************
  *   Copyright (c) 2019 Werner Mayer <wmayer[at]users.sourceforge.net>     *
  *                                                                         *
diff --git a/src/LibraryVersions.h.cmake b/src/LibraryVersions.h.cmake
index 4d9057ac81..eee40ce231 100644
--- a/src/LibraryVersions.h.cmake
+++ b/src/LibraryVersions.h.cmake
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #ifndef LIBRARY_VERSIONS_H
 #define LIBRARY_VERSIONS_H
 
diff --git a/src/SMESH_Version.h.cmake b/src/SMESH_Version.h.cmake
index 1e4084ecb2..6f518dd439 100644
--- a/src/SMESH_Version.h.cmake
+++ b/src/SMESH_Version.h.cmake
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #ifndef SMESH_VERSION_H
 #define SMESH_VERSION_H
 
diff --git a/src/__init__.py b/src/__init__.py
index e69de29bb2..8fbb285884 100644
--- a/src/__init__.py
+++ b/src/__init__.py
@@ -0,0 +1 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
\ No newline at end of file
diff --git a/src/boost_graph_adjacency_list.hpp b/src/boost_graph_adjacency_list.hpp
index 313a38ca60..a340ab9bc8 100644
--- a/src/boost_graph_adjacency_list.hpp
+++ b/src/boost_graph_adjacency_list.hpp
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #ifndef FREECAD_ADJACENCY_LIST_HPP_WORKAROUND
 #define FREECAD_ADJACENCY_LIST_HPP_WORKAROUND
 
diff --git a/src/boost_graph_reverse_graph.hpp b/src/boost_graph_reverse_graph.hpp
index 6a0cf88d74..34069782fe 100644
--- a/src/boost_graph_reverse_graph.hpp
+++ b/src/boost_graph_reverse_graph.hpp
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #ifndef FREECAD_REVERSE_GRAPH_HPP_WORKAROUND
 #define FREECAD_REVERSE_GRAPH_HPP_WORKAROUND
 
diff --git a/src/boost_regex.hpp b/src/boost_regex.hpp
index a08b52b5af..d9151c212c 100644
--- a/src/boost_regex.hpp
+++ b/src/boost_regex.hpp
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 #ifndef FREECAD_REGEX_HPP_WORKAROUND
 #define FREECAD_REGEX_HPP_WORKAROUND
 
diff --git a/src/config.h.cmake b/src/config.h.cmake
index 97c068e6cf..99eea7f857 100644
--- a/src/config.h.cmake
+++ b/src/config.h.cmake
@@ -1,3 +1,5 @@
+// SPDX-License-Identifier: LGPL-2.1-or-later
+
 /* config.h.  Generated from config.h.cmake by cmake.  */
 
 /* Define to 1 if you have the <bits/sigset.h> header file. */