diff --git a/export-html.cpp b/export-html.cpp
index 53b3a2791..86e2cb9c5 100644
--- a/export-html.cpp
+++ b/export-html.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /* Dirk Hohndel, 2015 */
 
 #include <QString>
diff --git a/subsurface-desktop-helper.cpp b/subsurface-desktop-helper.cpp
index f8d8ba1c7..34b04e928 100644
--- a/subsurface-desktop-helper.cpp
+++ b/subsurface-desktop-helper.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /* qt-gui.cpp */
 /* Qt UI implementation */
 #include "core/dive.h"
diff --git a/subsurface-desktop-main.cpp b/subsurface-desktop-main.cpp
index e38101302..bc2a4fc9d 100644
--- a/subsurface-desktop-main.cpp
+++ b/subsurface-desktop-main.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /* main.c */
 #include <locale.h>
 #include <stdio.h>
diff --git a/subsurface-mobile-helper.cpp b/subsurface-mobile-helper.cpp
index 8263f96c5..faaa31667 100644
--- a/subsurface-mobile-helper.cpp
+++ b/subsurface-mobile-helper.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /* qt-gui.cpp */
 /* Qt UI implementation */
 #include "core/dive.h"
diff --git a/subsurface-mobile-main.cpp b/subsurface-mobile-main.cpp
index 69b628ab9..c7f627fee 100644
--- a/subsurface-mobile-main.cpp
+++ b/subsurface-mobile-main.cpp
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /* main.c */
 #include <locale.h>
 #include <stdio.h>