diff --git a/changes/292.apichange.rst b/changes/292.apichange.rst
new file mode 100644
index 00000000..63c63b16
--- /dev/null
+++ b/changes/292.apichange.rst
@@ -0,0 +1 @@
+Add `outlier_detection` median calculators from jwst.
\ No newline at end of file
diff --git a/src/stcal/outlier_detection/median.py b/src/stcal/outlier_detection/median.py
index ed8da2f3..2ca6b7c2 100644
--- a/src/stcal/outlier_detection/median.py
+++ b/src/stcal/outlier_detection/median.py
@@ -6,6 +6,7 @@
 import tempfile
 import warnings
 from pathlib import Path
+from typing import Any
 
 import numpy as np
 
@@ -74,11 +75,12 @@ def __init__(self: MedianComputer,
         self.buffer_size = buffer_size
         self.dtype = dtype
         if self.in_memory:
-            self._median_computer = np.empty(full_shape, dtype=dtype)
+            computer: Any = np.empty(full_shape, dtype=dtype)
         else:
-            self._median_computer = OnDiskMedian(full_shape,
-                                                 dtype=dtype,
-                                                 buffer_size=buffer_size)
+            computer = OnDiskMedian(full_shape,
+                                    dtype=dtype,
+                                    buffer_size=buffer_size)
+        self._median_computer: Any = computer
 
     def append(self: MedianComputer,
                data: np.ndarray,
diff --git a/tests/outlier_detection/test_median.py b/tests/outlier_detection/test_median.py
index 3de71a87..48009475 100644
--- a/tests/outlier_detection/test_median.py
+++ b/tests/outlier_detection/test_median.py
@@ -16,7 +16,7 @@ def test_disk_appendable_array(tmpdir):
 
     slice_shape = (8,7)
     dtype = "float32"
-    tempdir = tmpdir / Path("tmptest")
+    tempdir = Path(tmpdir) / Path("tmptest")
     Path.mkdir(tempdir)
     fname = tempdir / "test.bin"
 
@@ -58,7 +58,7 @@ def test_disk_appendable_array_bad_inputs(tmpdir):
 
     slice_shape = (8, 7)
     dtype = "float32"
-    tempdir = tmpdir / Path("tmptest")
+    tempdir = Path(tmpdir) / Path("tmptest")
     fname = "test.bin"
 
     # test input directory does not exist
@@ -92,7 +92,7 @@ def test_on_disk_median(tmpdir):
     library_length = 3
     frame_shape = (21, 20)
     dtype = "float32"
-    tempdir = tmpdir / Path("tmptest")
+    tempdir = Path(tmpdir) / Path("tmptest")
     Path.mkdir(tempdir)
     shape = (library_length, *frame_shape)
 
@@ -171,7 +171,7 @@ def test_on_disk_median_bad_inputs(tmpdir):
     library_length = 3
     frame_shape = (21, 20)
     dtype = "float32"
-    tempdir = tmpdir / Path("tmptest")
+    tempdir = Path(tmpdir) / Path("tmptest")
     Path.mkdir(tempdir)
     shape = (library_length, *frame_shape)