diff --git a/src/core/errno.c b/src/core/errno.c
index b4f44cec..06905561 100644
--- a/src/core/errno.c
+++ b/src/core/errno.c
@@ -1,5 +1,7 @@
 #include <errno.h>
 
+FILE_LICENCE ( GPL2_OR_LATER );
+
 /** @file
  *
  * Error codes