diff --git a/bumpflatpakversionsha.py b/bumpflatpakversionsha.py
index 9331b51..b473f8c 100644
--- a/bumpflatpakversionsha.py
+++ b/bumpflatpakversionsha.py
@@ -1,62 +1,73 @@
 #
 # Copyright 2018  Aleix Pol Gonzalez <aleixpol@kde.org>
 # 
 # This program is free software; you can redistribute it and/or
 # modify it under the terms of the GNU General Public License as
 # published by the Free Software Foundation; either version 2 of
 # the License or (at your option) version 3 or any later version
 # accepted by the membership of KDE e.V. (or its successor approved
 # by the membership of KDE e.V.), which shall act as a proxy
 # defined in Section 14 of version 3 of the license.
 # 
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 # 
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
 import json
 import hashlib
 import requests
 import multiprocessing
 
 def calculate_sha256(url):
-    sha256 = hashlib.sha256()
+    urlsha = url + ".sha256"
+    r = requests.get(urlsha, stream=False)
+
+    if r.status_code == requests.codes.ok:
+        print("using", urlsha)
+        resp = r.text
+        idxEnd = resp.find(' ')
+        sha = resp[:idxEnd]
+        return sha
+    else:
+        print("no sha256 file", urlsha)
 
     print("getting...", url)
+    sha256 = hashlib.sha256()
     response = requests.get(url, stream=True)
 
     for data in response.iter_content():
         sha256.update(data)
     return sha256.hexdigest()
 
 def processModule(module):
     replace = {}
     for source in module['sources']:
         if source['type'] == 'archive':
             sha = calculate_sha256(source['url'])
             if sha != source['sha256']:
                 print("new sha", source, sha)
                 replace[source['sha256']] = sha
         break
     return replace
 
 if __name__ == "__main__":
     content = ""
     with open("org.kde.Sdk.json", 'r') as sdkfile:
         content = sdkfile.read()
 
     value = json.loads(content)
 
     pool = multiprocessing.Pool(6)
     replacements = pool.map(processModule, value['modules'])
 
     for repl in replacements:
         for (a, b) in repl.items():
             content = content.replace(a, b, 1)
 
     with open("org.kde.Sdk.json", 'w') as sdkfile:
         sdkfile.write(content)