diff --git a/riot/runtime/net/io_posix_stubs.c b/riot/runtime/net/io_posix_stubs.c
index 9ec0b332..97321671 100644
--- a/riot/runtime/net/io_posix_stubs.c
+++ b/riot/runtime/net/io_posix_stubs.c
@@ -1,6 +1,21 @@
 /*
 
-  This code taken from Eio's eio_posix_stub.c
+This code taken from Eio's eio_posix_stub.c, licensed as:
+
+Copyright (C) 2021 Anil Madhavapeddy  
+Copyright (C) 2022 Thomas Leonard  
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 */