diff --git a/model_server/accessors.py b/model_server/accessors.py
index 0e5e2cc9d827de70dae8a37688fe8af8c5b2def9..62df189d1f8157ffae3f415035574aa3ef81c697 100644
--- a/model_server/accessors.py
+++ b/model_server/accessors.py
@@ -189,7 +189,11 @@ def write_accessor_data_to_file(fpath: Path, accessor: GenericImageDataAccessor,
             [0, 1, 2, 3]
         )
         if accessor.is_mask():
-            tifffile.imwrite(fpath, zcyx.astype('uint8'), imagej=True)
+            if accessor.dtype == 'bool':
+                data = zcyx * 255
+            else:
+                data = zcyx.astype('uint8')
+            tifffile.imwrite(fpath, data, imagej=True)
         else:
             tifffile.imwrite(fpath, zcyx, imagej=True)
     except: