diff --git a/CHANGES.rst b/CHANGES.rst
index 1b4bad0..45a9218 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,14 @@
+===================
+STWCS Release Notes
+===================
+
+
+1.7.8 (TBD)
+-----------
+
+- Bug fix for empty scale value returned from idctab [#249]
+
+
 1.7.7 (2026-03-05)
 ------------------
 
diff --git a/stwcs/distortion/utils.py b/stwcs/distortion/utils.py
index 9fe555d..4608d33 100644
--- a/stwcs/distortion/utils.py
+++ b/stwcs/distortion/utils.py
@@ -111,12 +111,16 @@ def make_orthogonal_cd(wcs):
             pv += wcs.idctheta
         cs = np.cos(np.deg2rad(pv))
         sn = np.sin(np.deg2rad(pv))
+        
         pvmat = np.dot(np.array([[cs, sn], [-sn, cs]]), wcs.parity)
         rot = np.arctan2(pvmat[0, 1], pvmat[1, 1])
 
         det = linalg.det(wcs.parity)
         if hasattr(wcs, 'idcscale') and wcs.idcscale is not None:
             scale = (wcs.idcscale) / 3600.  # HST pixel scale provided
+        else:
+            warnings.warn("IDCSCALE is missing, computing it from CD matrix.")
+            scale = np.sqrt(np.abs(det))  # find as sqrt(pixel area)
     else:
 
         det = linalg.det(cd)