diff --git a/src/genl.c b/src/genl.c
index 099b317..a2826b5 100644
--- a/src/genl.c
+++ b/src/genl.c
@@ -1,3 +1,25 @@
+/* Generic Netlink helper functions */
+
+/* (C) 2014 by sysmocom - s.f.m.c. GmbH
+ * Author: Pablo Neira Ayuso <pablo@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * 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 Affero 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 <unistd.h>
diff --git a/src/gtp-genl.c b/src/gtp-genl.c
index c7a0522..c1f60ab 100644
--- a/src/gtp-genl.c
+++ b/src/gtp-genl.c
@@ -1,3 +1,25 @@
+/* GTP specific Generic Netlink helper functions */
+
+/* (C) 2014 by sysmocom - s.f.m.c. GmbH
+ * Author: Pablo Neira Ayuso <pablo@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * 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 Affero 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/src/gtp-rtnl.c b/src/gtp-rtnl.c
index 6ecea08..22b9430 100644
--- a/src/gtp-rtnl.c
+++ b/src/gtp-rtnl.c
@@ -1,3 +1,25 @@
+/* GTP specific RTNetlink helper functions */
+
+/* (C) 2014 by sysmocom - s.f.m.c. GmbH
+ * Author: Pablo Neira Ayuso <pablo@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * 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 Affero 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 <unistd.h>
diff --git a/src/gtp.c b/src/gtp.c
index 1986954..4534091 100644
--- a/src/gtp.c
+++ b/src/gtp.c
@@ -1,3 +1,25 @@
+/* External interface functions of the library */
+
+/* (C) 2014 by sysmocom - s.f.m.c. GmbH
+ * Author: Pablo Neira Ayuso <pablo@gnumonks.org>
+ *
+ * All Rights Reserved
+ *
+ * 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 Affero 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 <stdlib.h>
 #include <netinet/in.h>