diff --git a/kimimaro/intake.py b/kimimaro/intake.py
index 318ca05..a9a88af 100644
--- a/kimimaro/intake.py
+++ b/kimimaro/intake.py
@@ -648,7 +648,7 @@ def paint_walls(binimg):
       changed.add(fruit)
       binimg |= (cc_labels[slc] == fruit)
 
-    fruit = np.cast[cc_labels.dtype](fruit)
+    fruit = np.asarray(fruit, dtype=cc_labels.dtype)
     binimg, N = fill_voids.fill(binimg, in_place=True, return_fill_count=True)
     cc_labels[slc] *= ~binimg
     cc_labels[slc] += fruit * binimg