diff --git a/test/functional/api/cas/casadm.py b/test/functional/api/cas/casadm.py
index dfce8ab..cc95a3b 100644
--- a/test/functional/api/cas/casadm.py
+++ b/test/functional/api/cas/casadm.py
@@ -133,9 +133,9 @@ def remove_detached(core_device: Device, shortcut: bool = False):
     return output
 
 
-def try_add(core_device: Device, cache_id: int, core_id: int = None):
+def try_add(core_device: Device, cache_id: int, core_id: int):
     output = TestRun.executor.run(script_try_add_cmd(str(cache_id), core_device.path,
-                                                     str(core_id) if core_id is not None else None))
+                                                     str(core_id)))
     if output.exit_code != 0:
         raise CmdException("Failed to execute try add script command.", output)
     return Core(core_device.path, cache_id)