diff --git a/weboob/core/ouiboube.py b/weboob/core/ouiboube.py
index 317fd511..f9f5b98d 100644
--- a/weboob/core/ouiboube.py
+++ b/weboob/core/ouiboube.py
@@ -204,8 +204,8 @@ class WebNip(object):
         :rtype: iter[:class:`weboob.tools.backend.Module`]
         """
         for _, backend in sorted(self.backend_instances.iteritems()):
-            if caps is None or backend.has_caps(caps) and \
-               module is None or backend.NAME == module:
+            if (caps is None or backend.has_caps(caps)) and \
+               (module is None or backend.NAME == module):
                 with backend:
                     yield backend