diff --git a/src/calibre/ebooks/metadata/sources/update.py b/src/calibre/ebooks/metadata/sources/update.py
index c76b6cb6cf..44969d43f6 100644
--- a/src/calibre/ebooks/metadata/sources/update.py
+++ b/src/calibre/ebooks/metadata/sources/update.py
@@ -20,7 +20,7 @@ from calibre.utils.https import get_https_resource_securely
 
 cache = JSONConfig('metadata-sources-cache.json')
 
-UPDATE_INTERVAL = 24 * 60 * 60
+UPDATE_INTERVAL = 12 * 60 * 60
 
 current_search_engines = builtin_search_engines
 
@@ -113,6 +113,7 @@ def main(report_error=prints, report_action=prints):
                 'Failed to get metadata sources hashes with error: {}'.format(as_unicode(e)))
             return
         if not needed:
+            cache.touch()
             return
         updated = {}
         for name, expected_hash in needed.iteritems():
diff --git a/src/calibre/utils/config.py b/src/calibre/utils/config.py
index ce69cd56c8..e921b73e19 100644
--- a/src/calibre/utils/config.py
+++ b/src/calibre/utils/config.py
@@ -292,6 +292,12 @@ class XMLConfig(dict):
         except EnvironmentError:
             return 0
 
+    def touch(self):
+        try:
+            os.utime(self.file_path, None)
+        except EnvironmentError:
+            pass
+
     def raw_to_object(self, raw):
         return plistlib.readPlistFromString(raw)