diff --git a/src/libcmd/built-path.cc b/src/libcmd/built-path.cc
index 6ff99070d..0eec32e36 100644
--- a/src/libcmd/built-path.cc
+++ b/src/libcmd/built-path.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "built-path.hh"
 #include "derivations.hh"
 #include "store-api.hh"
diff --git a/src/libcmd/built-path.hh b/src/libcmd/built-path.hh
index da87a33b0..82da68543 100644
--- a/src/libcmd/built-path.hh
+++ b/src/libcmd/built-path.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 #include "derived-path.hh"
diff --git a/src/libcmd/cmd-profiles.cc b/src/libcmd/cmd-profiles.cc
index 8a04100f6..fc4af51c7 100644
--- a/src/libcmd/cmd-profiles.cc
+++ b/src/libcmd/cmd-profiles.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include <set>
 
 #include "cmd-profiles.hh"
diff --git a/src/libcmd/cmd-profiles.hh b/src/libcmd/cmd-profiles.hh
index 2185daa34..cd17a993a 100644
--- a/src/libcmd/cmd-profiles.hh
+++ b/src/libcmd/cmd-profiles.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/command.cc b/src/libcmd/command.cc
index de9f546fc..cc13dbf04 100644
--- a/src/libcmd/command.cc
+++ b/src/libcmd/command.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "command.hh"
 #include "store-api.hh"
 #include "local-fs-store.hh"
diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index 6c6c81718..6931c67ee 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/common-eval-args.cc b/src/libcmd/common-eval-args.cc
index 9a7c30d57..c31f5e708 100644
--- a/src/libcmd/common-eval-args.cc
+++ b/src/libcmd/common-eval-args.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "eval-settings.hh"
 #include "common-eval-args.hh"
 #include "shared.hh"
diff --git a/src/libcmd/common-eval-args.hh b/src/libcmd/common-eval-args.hh
index 08a4b65e4..192add8ba 100644
--- a/src/libcmd/common-eval-args.hh
+++ b/src/libcmd/common-eval-args.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/editor-for.cc b/src/libcmd/editor-for.cc
index 67653d9c9..063f75a39 100644
--- a/src/libcmd/editor-for.cc
+++ b/src/libcmd/editor-for.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "editor-for.hh"
 #include "environment-variables.hh"
 #include "source-path.hh"
diff --git a/src/libcmd/editor-for.hh b/src/libcmd/editor-for.hh
index 8acd7011e..9070e9cb4 100644
--- a/src/libcmd/editor-for.hh
+++ b/src/libcmd/editor-for.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/installable-attr-path.cc b/src/libcmd/installable-attr-path.cc
index eb15fecc3..d7ee5ab17 100644
--- a/src/libcmd/installable-attr-path.cc
+++ b/src/libcmd/installable-attr-path.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "globals.hh"
 #include "installable-attr-path.hh"
 #include "outputs-spec.hh"
diff --git a/src/libcmd/installable-attr-path.hh b/src/libcmd/installable-attr-path.hh
index 86c2f8219..75e173032 100644
--- a/src/libcmd/installable-attr-path.hh
+++ b/src/libcmd/installable-attr-path.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/installable-derived-path.cc b/src/libcmd/installable-derived-path.cc
index 4d1f83a1c..79f23915f 100644
--- a/src/libcmd/installable-derived-path.cc
+++ b/src/libcmd/installable-derived-path.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "installable-derived-path.hh"
 #include "derivations.hh"
 
diff --git a/src/libcmd/installable-derived-path.hh b/src/libcmd/installable-derived-path.hh
index e0b4f18b3..ec7da7e86 100644
--- a/src/libcmd/installable-derived-path.hh
+++ b/src/libcmd/installable-derived-path.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/installable-flake.cc b/src/libcmd/installable-flake.cc
index b1ebd339e..923b13d4e 100644
--- a/src/libcmd/installable-flake.cc
+++ b/src/libcmd/installable-flake.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "globals.hh"
 #include "installable-flake.hh"
 #include "installable-derived-path.hh"
diff --git a/src/libcmd/installable-flake.hh b/src/libcmd/installable-flake.hh
index 314918c14..40d174946 100644
--- a/src/libcmd/installable-flake.hh
+++ b/src/libcmd/installable-flake.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/installable-value.cc b/src/libcmd/installable-value.cc
index c8a3e1b21..11b3a4f8c 100644
--- a/src/libcmd/installable-value.cc
+++ b/src/libcmd/installable-value.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "installable-value.hh"
 #include "eval-cache.hh"
 #include "fetch-to-store.hh"
diff --git a/src/libcmd/installable-value.hh b/src/libcmd/installable-value.hh
index 3138ce8ec..af5c9bc7d 100644
--- a/src/libcmd/installable-value.hh
+++ b/src/libcmd/installable-value.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 711cf1b07..532886d77 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "globals.hh"
 #include "installables.hh"
 #include "installable-derived-path.hh"
diff --git a/src/libcmd/installables.hh b/src/libcmd/installables.hh
index 95e8841ca..9875a57a7 100644
--- a/src/libcmd/installables.hh
+++ b/src/libcmd/installables.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/legacy.cc b/src/libcmd/legacy.cc
index 6df09ee37..ffb0ff406 100644
--- a/src/libcmd/legacy.cc
+++ b/src/libcmd/legacy.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "legacy.hh"
 
 namespace nix {
diff --git a/src/libcmd/legacy.hh b/src/libcmd/legacy.hh
index 357500a4d..4905ac8aa 100644
--- a/src/libcmd/legacy.hh
+++ b/src/libcmd/legacy.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/markdown.cc b/src/libcmd/markdown.cc
index dbaab8c19..e074aaa4d 100644
--- a/src/libcmd/markdown.cc
+++ b/src/libcmd/markdown.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "markdown.hh"
 #include "error.hh"
 #include "finally.hh"
diff --git a/src/libcmd/markdown.hh b/src/libcmd/markdown.hh
index a04d32a4f..3511513df 100644
--- a/src/libcmd/markdown.hh
+++ b/src/libcmd/markdown.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file
 
diff --git a/src/libcmd/meson.build b/src/libcmd/meson.build
index 73deb035c..bf89933ff 100644
--- a/src/libcmd/meson.build
+++ b/src/libcmd/meson.build
@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+#
+# SPDX-License-Identifier: LGPL-2.1-only
+
 libcmd_sources = files(
   'built-path.cc',
   'cmd-profiles.cc',
diff --git a/src/libcmd/repl-interacter.cc b/src/libcmd/repl-interacter.cc
index 0cf4e34b8..3be6c72fa 100644
--- a/src/libcmd/repl-interacter.cc
+++ b/src/libcmd/repl-interacter.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include "error.hh"
 #include "file-system.hh"
 #include "logging.hh"
diff --git a/src/libcmd/repl-interacter.hh b/src/libcmd/repl-interacter.hh
index 8f815fceb..620da6a3f 100644
--- a/src/libcmd/repl-interacter.hh
+++ b/src/libcmd/repl-interacter.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 /// @file
 
diff --git a/src/libcmd/repl-overlays.nix b/src/libcmd/repl-overlays.nix
index 1488d13ac..a85965831 100644
--- a/src/libcmd/repl-overlays.nix
+++ b/src/libcmd/repl-overlays.nix
@@ -1,3 +1,7 @@
+# SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+#
+# SPDX-License-Identifier: LGPL-2.1-only
+
 info: initial: functions:
 let
   final = builtins.foldl' (prev: function: prev // (function info final prev)) initial functions;
diff --git a/src/libcmd/repl.cc b/src/libcmd/repl.cc
index bb9225ce5..62474cfe7 100644
--- a/src/libcmd/repl.cc
+++ b/src/libcmd/repl.cc
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #include <cstdio>
 #include <editline.h>
 #include <iostream>
diff --git a/src/libcmd/repl.hh b/src/libcmd/repl.hh
index aac79ec74..41b210309 100644
--- a/src/libcmd/repl.hh
+++ b/src/libcmd/repl.hh
@@ -1,3 +1,7 @@
+// SPDX-FileCopyrightText: 2024 Nix and Lix Authors
+//
+// SPDX-License-Identifier: LGPL-2.1-only
+
 #pragma once
 ///@file