diff --git a/fdroidserver/index.py b/fdroidserver/index.py
index 61552138..56caaad1 100644
--- a/fdroidserver/index.py
+++ b/fdroidserver/index.py
@@ -32,7 +32,7 @@ import urllib.parse
 import zipfile
 import calendar
 from binascii import hexlify, unhexlify
-from datetime import datetime
+from datetime import datetime, timezone
 from xml.dom.minidom import Document
 
 from . import _
@@ -67,7 +67,7 @@ def make(apps, sortedids, apks, repodir, archive):
         common.assert_config_keystore(common.config)
 
     repodict = collections.OrderedDict()
-    repodict['timestamp'] = datetime.utcnow()
+    repodict['timestamp'] = datetime.utcnow().replace(tzinfo=timezone.utc)
     repodict['version'] = METADATA_VERSION
 
     if common.config['repo_maxage'] != 0:
diff --git a/tests/run-tests b/tests/run-tests
index aadd82f1..9ab5a9b6 100755
--- a/tests/run-tests
+++ b/tests/run-tests
@@ -258,6 +258,10 @@ if [ "$TRAVIS_OS_NAME" != "osx" ]; then
     ! test -e repo/index.xml.asc
 fi
 
+v0timestamp=`$sed -n -e 's,.*timestamp="\([0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]\)".*,\1,p' repo/index.xml`
+v1timestamp=`$sed -n -e 's,.*"timestamp": \([0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]\).*,\1,p' repo/index-v1.json`
+test $v0timestamp -eq $v1timestamp
+
 # we can't easily reproduce the timestamps for things, so just hardcode them
 $sed -i.tmp -e 's,timestamp="[0-9]*",timestamp="1480431575",' repo/index.xml
 diff -uw $WORKSPACE/tests/repo/index.xml repo/index.xml