diff --git a/test/functional/api/cas/cache.py b/test/functional/api/cas/cache.py
index eb0ab27..6fd4aa9 100644
--- a/test/functional/api/cas/cache.py
+++ b/test/functional/api/cas/cache.py
@@ -177,8 +177,7 @@ class Cache:
                                               if alru_params.staleness_time else None,
                                               alru_params.flush_max_buffers
                                               if alru_params.flush_max_buffers else None,
-                                              int(alru_params.activity_threshold.total_seconds()
-                                                  * 1000)
+                                              alru_params.activity_threshold.total_milliseconds()
                                               if alru_params.activity_threshold else None)
 
     def get_cache_config(self):
diff --git a/test/functional/api/cas/cache_config.py b/test/functional/api/cas/cache_config.py
index 2af69af..0908cb9 100644
--- a/test/functional/api/cas/cache_config.py
+++ b/test/functional/api/cas/cache_config.py
@@ -6,7 +6,7 @@
 from enum import IntEnum
 from aenum import Enum
 from test_utils.size import Size, Unit
-from datetime import timedelta
+from attotime import attotimedelta
 
 
 class CacheLineSize(Enum):
@@ -79,7 +79,7 @@ class CacheStatus(Enum):
     incomplete = 5
 
 
-class Time(timedelta):
+class Time(attotimedelta):
     def total_milliseconds(self):
         return int(self.total_seconds() * 1000)