diff --git a/test/functional/api/cas/casadm.py b/test/functional/api/cas/casadm.py
index 3ac59dfb2..098830139 100644
--- a/test/functional/api/cas/casadm.py
+++ b/test/functional/api/cas/casadm.py
@@ -516,5 +516,5 @@ def remove_all_detached_cores() -> None:
     from api.cas.casadm_parser import get_cas_devices_dict
 
     devices = get_cas_devices_dict()
-    for dev in devices["core_pool"]:
-        TestRun.executor.run(remove_detached_cmd(dev["device"]))
+    for dev in devices["core_pool"].values():
+        TestRun.executor.run(remove_detached_cmd(dev["device_path"]))