diff --git a/tests/functional/pyocf/types/cache.py b/tests/functional/pyocf/types/cache.py
index c6d5118..6aaae05 100644
--- a/tests/functional/pyocf/types/cache.py
+++ b/tests/functional/pyocf/types/cache.py
@@ -296,7 +296,7 @@ class Cache:
 
     def standby_detach(self):
         self.write_lock()
-        c = OcfCompletion([("cache", c_void_p), ("priv", c_void_p), ("error", c_int)])
+        c = OcfCompletion([("priv", c_void_p), ("error", c_int)])
         self.owner.lib.ocf_mngt_cache_standby_detach(self, c, None)
         c.wait()
         self.write_unlock()