diff --git a/pyopencl/algorithm.py b/pyopencl/algorithm.py
index 328a1f774189fcd8d2847ba29c9259b3252a3962..e256b5786cd6050425a7c2956209b90a2d6c9a0b 100644
--- a/pyopencl/algorithm.py
+++ b/pyopencl/algorithm.py
@@ -1039,7 +1039,7 @@ class ListOfListsBuilder:
         if self.debug:
             gsize = (1,)
             lsize = (1,)
-        elif self.complex_kernel and queue.device.type == cl.device_type.CPU:
+        elif self.do_not_vectorize():
             gsize = (4*queue.device.max_compute_units,)
             lsize = (1,)
         else: