diff --git a/tests/functional/pyocf/types/data.py b/tests/functional/pyocf/types/data.py
index 6243e12..c4054c6 100644
--- a/tests/functional/pyocf/types/data.py
+++ b/tests/functional/pyocf/types/data.py
@@ -21,7 +21,7 @@ from enum import IntEnum
 from hashlib import md5
 import weakref
 
-from ..utils import print_buffer
+from ..utils import print_buffer, Size as S
 
 
 class DataSeek(IntEnum):
diff --git a/tests/functional/pyocf/utils.py b/tests/functional/pyocf/utils.py
index 643f675..a0710af 100644
--- a/tests/functional/pyocf/utils.py
+++ b/tests/functional/pyocf/utils.py
@@ -56,9 +56,13 @@ class Size:
     _MiB = _KiB * 1024
     _GiB = _MiB * 1024
     _TiB = _GiB * 1024
+    _SECTOR_SIZE = 512
 
-    def __init__(self, b: int):
-        self.bytes = b
+    def __init__(self, b: int, sector_aligned: bool = False):
+        if sector_aligned:
+            self.bytes = ((b + self._SECTOR_SIZE - 1) // self._SECTOR_SIZE) * self._SECTOR_SIZE
+        else:
+            self.bytes = b
 
     def __int__(self):
         return self.bytes
@@ -67,24 +71,28 @@ class Size:
         return self.bytes
 
     @classmethod
-    def from_B(cls, value):
-        return cls(value)
+    def from_B(cls, value, sector_aligned = False):
+        return cls(value, sector_aligned)
 
     @classmethod
-    def from_KiB(cls, value):
-        return cls(value * cls._KiB)
+    def from_KiB(cls, value, sector_aligned = False):
+        return cls(value * cls._KiB, sector_aligned)
 
     @classmethod
-    def from_MiB(cls, value):
-        return cls(value * cls._MiB)
+    def from_MiB(cls, value, sector_aligned = False):
+        return cls(value * cls._MiB, sector_aligned)
 
     @classmethod
-    def from_GiB(cls, value):
-        return cls(value * cls._GiB)
+    def from_GiB(cls, value, sector_aligned = False):
+        return cls(value * cls._GiB, sector_aligned)
 
     @classmethod
-    def from_TiB(cls, value):
-        return cls(value * cls._TiB)
+    def from_TiB(cls, value, sector_aligned = False):
+        return cls(value * cls._TiB, sector_aligned)
+
+    @classmethod
+    def from_sector(cls, value):
+        return cls(value * cls._SECTOR_SIZE)
 
     @property
     def B(self):
@@ -106,6 +114,10 @@ class Size:
     def TiB(self):
         return self.bytes / self._TiB
 
+    @property
+    def sectors(self):
+        return self.bytes // _SECTOR_SIZE
+
     def __str__(self):
         if self.bytes < self._KiB:
             return "{} B".format(self.B)
diff --git a/tests/functional/tests/engine/test_wo.py b/tests/functional/tests/engine/test_wo.py
index 012d74c..2ea0b60 100644
--- a/tests/functional/tests/engine/test_wo.py
+++ b/tests/functional/tests/engine/test_wo.py
@@ -93,7 +93,7 @@ def test_wo_read_data_consistency(pyocf_ctx):
     # possible end sectors for test iteration
     end_sec = [8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 23]
 
-    SECTOR_SIZE = 512
+    SECTOR_SIZE = Size.from_sector(1).B
     CACHELINE_SIZE = 4096
     WORKSET_SIZE = 3 * CACHELINE_SIZE
     WORKSET_OFFSET = 1024 * CACHELINE_SIZE