diff --git a/Makefile b/Makefile
index 60bfa1c..2c4ddde 100644
--- a/Makefile
+++ b/Makefile
@@ -1,3 +1,19 @@
+#
+# Copyright (C) 2023 Yuichi Nakamura (@yunkya2)
+#
+# 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 3 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.  If not, see <http://www.gnu.org/licenses/>.
+#
 CROSS = m68k-xelf-
 CC = $(CROSS)gcc
 AS = $(CROSS)gcc
diff --git a/gdbserver.c b/gdbserver.c
index 9f1fef8..04ae7b8 100644
--- a/gdbserver.c
+++ b/gdbserver.c
@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2023 Yuichi Nakamura (@yunkya2)
+ * Based upon gdbserver.c by @bet4it
+ *
+ * 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 3 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.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/packets.c b/packets.c
index 2499b10..0115740 100644
--- a/packets.c
+++ b/packets.c
@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2023 Yuichi Nakamura (@yunkya2)
+ * Based upon packets.c by @bet4it
+ *
+ * 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 3 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.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 // Many codes in this file was borrowed from GdbConnection.cc in rr
 #include <fcntl.h>
 #include <stdio.h>
diff --git a/packets.h b/packets.h
index cd9f670..ae83c5b 100644
--- a/packets.h
+++ b/packets.h
@@ -1,3 +1,21 @@
+/*
+ * Copyright (C) 2023 Yuichi Nakamura (@yunkya2)
+ * Based upon packets.h by @bet4it
+ *
+ * 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 3 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.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 #ifndef PACKETS_H
 #define PACKETS_H
 
diff --git a/ptrace.c b/ptrace.c
index 3223d23..9214bfa 100644
--- a/ptrace.c
+++ b/ptrace.c
@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2023 Yuichi Nakamura (@yunkya2)
+ *
+ * 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 3 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.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 #include <stdio.h>
 #include <stddef.h>
 #include <string.h>
diff --git a/ptrace.h b/ptrace.h
index 26de4e4..a32d755 100644
--- a/ptrace.h
+++ b/ptrace.h
@@ -1,3 +1,20 @@
+/*
+ * Copyright (C) 2023 Yuichi Nakamura (@yunkya2)
+ *
+ * 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 3 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.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
 #ifndef _PTRACE_H
 #define _PTRACE_H