diff --git a/weboob/browser/browsers.py b/weboob/browser/browsers.py
index d3b8dc27cb708196f7d86f9fb8f4faa2e82ab1d0..24f5f608162b40dd7a78df52519923c4196df47b 100644
--- a/weboob/browser/browsers.py
+++ b/weboob/browser/browsers.py
@@ -877,7 +877,7 @@ def dump_state(self):
         state = {}
         if hasattr(self, 'page') and self.page:
             state['url'] = self.page.url
-        state['cookies'] = base64.b64encode(zlib.compress(pickle.dumps(self.session.cookies, -1)))
+        state['cookies'] = base64.b64encode(zlib.compress(pickle.dumps(self.session.cookies, -1))).decode('ascii')
         for attrname in self.__states__:
             try:
                 state[attrname] = getattr(self, attrname)