diff --git a/fdroidserver/update.py b/fdroidserver/update.py
index ee25daf6..ce1934fe 100644
--- a/fdroidserver/update.py
+++ b/fdroidserver/update.py
@@ -528,19 +528,10 @@ def make_index(apps, apks, repodir, archive, categories):
                     if 'added' in apk:
                         addElement('added', time.strftime('%Y-%m-%d', apk['added']), doc, apkel)
                     perms = ""
-                    for p in apk['permissions']:
-                        if len(perms) > 0:
-                            perms += ","
-                        perms += p
-                    if len(perms) > 0:
-                        addElement('permissions', perms, doc, apkel)
-                    features = ""
-                    for f in apk['features']:
-                        if len(features) > 0:
-                            features += ","
-                        features += f
-                    if len(features) > 0:
-                        addElement('features', features, doc, apkel)
+                    if len(apk['permissions']) > 0:
+                        addElement('permissions', ','.join(apk['permissions']), doc, apkel)
+                    if len(apk['features') > 0:
+                        addElement('features', ','.join(apk['features']), doc, apkel)
 
     of = open(os.path.join(repodir, 'index.xml'), 'wb')
     if options.pretty: