diff --git a/include/CustomTextKnob.h b/include/CustomTextKnob.h
index 23b7e8b1f..25bba1315 100644
--- a/include/CustomTextKnob.h
+++ b/include/CustomTextKnob.h
@@ -1,4 +1,27 @@
-/* Text customizable knob */
+/*
+ * CustomTextKnob.h
+ *
+ * Copyright (c) 2020 Ibuki Sugiyama <main/at/fuwa.dev>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
 #ifndef LMMS_GUI_CUSTOM_TEXT_KNOB_H
 #define LMMS_GUI_CUSTOM_TEXT_KNOB_H
 
diff --git a/src/gui/widgets/CustomTextKnob.cpp b/src/gui/widgets/CustomTextKnob.cpp
index 9f6e19b90..ce880608c 100644
--- a/src/gui/widgets/CustomTextKnob.cpp
+++ b/src/gui/widgets/CustomTextKnob.cpp
@@ -1,3 +1,27 @@
+/*
+ * CustomTextKnob.cpp
+ *
+ * Copyright (c) 2020 Ibuki Sugiyama <main/at/fuwa.dev>
+ *
+ * This file is part of LMMS - https://lmms.io
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program (see COPYING); if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301 USA.
+ *
+ */
+
 #include "CustomTextKnob.h"
 
 namespace lmms::gui