diff --git a/rng-tools.spec b/rng-tools.spec
index 2f5d2ea..2d81463 100644
--- a/rng-tools.spec
+++ b/rng-tools.spec
@@ -10,6 +10,7 @@ License:        GPLv2+
 URL:            http://sourceforge.net/projects/gkernel/
 Source0:        http://downloads.sourceforge.net/project/gkernel/rng-tools/4/rng-tools-%{version}.tar.gz
 Source1:        rngd.service
+# https://sourceforge.net/p/gkernel/patches/111/
 Patch0:         rngd-exit-code.patch
 
 BuildRequires:  gettext