diff --git a/aclocal/ax_lib_event.m4 b/aclocal/ax_lib_event.m4
index 4193a7b..3a48156 100644
--- a/aclocal/ax_lib_event.m4
+++ b/aclocal/ax_lib_event.m4
@@ -27,6 +27,11 @@
 dnl @category C
 dnl @version 2007-09-12
 dnl @license AllPermissive
+dnl
+dnl Copyright (C) 2009 David Reiss
+dnl Copying and distribution of this file, with or without modification,
+dnl are permitted in any medium without royalty provided the copyright
+dnl notice and this notice are preserved.
 
 dnl Input: ax_libevent_path, WANT_LIBEVENT_VERSION
 dnl Output: success=yes/no