diff --git a/hips/draw/ui.py b/hips/draw/ui.py
index b12ee19..75981f4 100644
--- a/hips/draw/ui.py
+++ b/hips/draw/ui.py
@@ -116,10 +116,10 @@ def write_image(self, filename: str, overwrite: bool = False) -> None:
 
         if self.tile_format == 'fits':
             hdu = fits.PrimaryHDU(data=self.image, header=self.geometry.fits_header)
-            hdu.writeto(filename)
+            hdu.writeto(filename, overwrite=overwrite)
         else:
             image = Image.fromarray(self.image)
-            image.save(filename)
+            image.save(filename, overwrite=overwrite)
 
     def plot(self, show_grid: bool = False) -> None:
         """Plot the all sky image and overlay HiPS tile outlines.