diff --git a/jwst/skymatch/skyimage.py b/jwst/skymatch/skyimage.py
index 65bc943bec..8a6ca6f3c8 100644
--- a/jwst/skymatch/skyimage.py
+++ b/jwst/skymatch/skyimage.py
@@ -619,7 +619,7 @@ def calc_sky(self, overlap=None, delta=True):
                     continue
 
                 # set pixels in 'fill_mask' that are inside a polygon to True:
-                x, y = self.wcs_inv(ra, dec)
+                x, y = self.wcs_inv(ra, dec, with_bounding_box=False)
                 poly_vert = list(zip(*[x, y]))
 
                 polygon = region.Polygon(True, poly_vert)