diff --git a/drizzle/resample.py b/drizzle/resample.py
index 5539d0d..dffe4ca 100644
--- a/drizzle/resample.py
+++ b/drizzle/resample.py
@@ -411,8 +411,7 @@ def _alloc_output_arrays(self, out_shape, max_ctx_id, out_img, out_wht,
                     )
 
         if out_img is None:
-            self._out_img = np.empty(out_shape, dtype=np.float32)
-            self._out_img.fill(self._fillval)
+            self._out_img = np.zeros(out_shape, dtype=np.float32)
         else:
             self._out_img = out_img