diff --git a/sa_cmd.c b/sa_cmd.c
index 94176f6..88f43a9 100644
--- a/sa_cmd.c
+++ b/sa_cmd.c
@@ -1,3 +1,22 @@
+/* Copyright (c) 2020, Erik Kaashoek erik@kaashoek.com
+ * All rights reserved.
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * The software 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
 
 extern volatile int SI4432_Sel;         // currently selected SI4432
 void SI4432_Write_Byte(byte ADR, byte DATA );
diff --git a/sa_core.c b/sa_core.c
index 81e2957..dfc8c32 100644
--- a/sa_core.c
+++ b/sa_core.c
@@ -1,3 +1,23 @@
+/* Copyright (c) 2020, Erik Kaashoek erik@kaashoek.com
+ * All rights reserved.
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * The software 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+
 #include "SI4432.h"		// comment out for simulation
 
 int dirty = true;
diff --git a/si4432.c b/si4432.c
index d855249..aef77b8 100644
--- a/si4432.c
+++ b/si4432.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2014-2015, TAKAHASHI Tomohiro (TTRFTECH) edy555@gmail.com
+/* Copyright (c) 2020, Erik Kaashoek erik@kaashoek.com
  * All rights reserved.
  *
  * This is free software; you can redistribute it and/or modify
@@ -16,6 +16,8 @@
  * the Free Software Foundation, Inc., 51 Franklin Street,
  * Boston, MA 02110-1301, USA.
  */
+
+
 #include "ch.h"
 #include "hal.h"
 #include "nanovna.h"
diff --git a/si4432.h b/si4432.h
index 8473302..679f108 100644
--- a/si4432.h
+++ b/si4432.h
@@ -1,3 +1,23 @@
+/* Copyright (c) 2020, Erik Kaashoek erik@kaashoek.com
+ * All rights reserved.
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * The software 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+
 #ifndef __SI4432_H__
 
 #define __SI4432_H__
diff --git a/ui_sa.c b/ui_sa.c
index e4904fb..20022f6 100644
--- a/ui_sa.c
+++ b/ui_sa.c
@@ -1,3 +1,24 @@
+/* Copyright (c) 2020, Erik Kaashoek erik@kaashoek.com
+ * All rights reserved.
+ *
+ * This 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 3, or (at your option)
+ * any later version.
+ *
+ * The software 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 GNU Radio; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+
+
 void markmap_all_markers(void);
 static void menu_marker_modify_cb(int item, uint8_t data);
 extern const menuitem_t menu_marker_modify[];