diff --git a/rear.spec b/rear.spec
index fb65ee1..8d75934 100644
--- a/rear.spec
+++ b/rear.spec
@@ -8,8 +8,7 @@ Summary: Relax-and-Recover is a Linux disaster recovery and system migration too
 URL: http://relax-and-recover.org/
 License: GPLv3
 
-# as GitHub stopped with download section we need to go back to Sourceforge for downloads
-Source0: https://sourceforge.net/projects/rear/files/rear/%{version}/rear-%{version}.tar.gz
+Source0: https://github.com/rear/rear/archive/%{version}.tar.gz#/rear-%{version}.tar.gz
 # Add cronjob and systemd timer as documentation
 Source1: rear.cron
 Source2: rear.service
@@ -92,7 +91,13 @@ sed -e 's:/lib/:/usr/lib/:g' \
 
 %build
 # build HTML user guide
-make doc
+# asciidoc writes a timestamp to files it produces, based on the last
+# modified date of the source file, but is sensitive to the timezone.
+# This makes the results differ according to the timezone of the build machine
+# and spurious changes will be seen.
+# Set the timezone to UTC as a workaround.
+# https://wiki.debian.org/ReproducibleBuilds/TimestampsInDocumentationGeneratedByAsciidoc
+TZ=UTC make doc
 
 %install
 %{make_install}