diff --git a/docs/doxygen/Doxyfile.in b/docs/doxygen/Doxyfile.in
index 852844860..3ec3ef60d 100644
--- a/docs/doxygen/Doxyfile.in
+++ b/docs/doxygen/Doxyfile.in
@@ -1,5 +1,9 @@
 # Doxyfile 1.9.3
 
+#
+# SPDX-FileCopyrightText: 2011-2021 Carles Fernandez-Prades <carles.fernandez(at)cttc.es>
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
 # This file describes the settings to be used by the documentation system
 # doxygen (www.doxygen.org) for a project.
 #
diff --git a/src/algorithms/libs/volk_gnsssdr_module/volk_gnsssdr/Doxyfile.in b/src/algorithms/libs/volk_gnsssdr_module/volk_gnsssdr/Doxyfile.in
index a63402977..24696f8d0 100644
--- a/src/algorithms/libs/volk_gnsssdr_module/volk_gnsssdr/Doxyfile.in
+++ b/src/algorithms/libs/volk_gnsssdr_module/volk_gnsssdr/Doxyfile.in
@@ -1,5 +1,9 @@
 # Doxyfile 1.9.3
 
+#
+# SPDX-FileCopyrightText: 2011-2021 Carles Fernandez-Prades <carles.fernandez(at)cttc.es>
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
 # This file describes the settings to be used by the documentation system
 # doxygen (www.doxygen.org) for a project.
 #