diff --git a/sumpy/fmm.py b/sumpy/fmm.py
index 231013b9cbb1e7c7b011d8e891ce54203c320590..f71f350cbea1c61bc19a3fc4db0c1886b2554f2f 100644
--- a/sumpy/fmm.py
+++ b/sumpy/fmm.py
@@ -539,12 +539,18 @@ class SumpyExpansionWrangler(ExpansionWranglerInterface):
 
         return obj_array_vectorize(reorder, potentials)
 
-    def get_max_nsources_in_one_box(self, queue):
-        return int(pyopencl.array.max(self.tree.box_source_counts_nonchild,
+    @property
+    @memoize_method
+    def max_nsources_in_one_box(self):
+        with cl.CommandQueue(self.tree_indep.cl_context) as queue:
+            return int(pyopencl.array.max(self.tree.box_source_counts_nonchild,
                 queue).get())
 
-    def get_max_ntargets_in_one_box(self, queue):
-        return int(pyopencl.array.max(self.tree.box_target_counts_nonchild,
+    @property
+    @memoize_method
+    def max_ntargets_in_one_box(self):
+        with cl.CommandQueue(self.tree_indep.cl_context) as queue:
+            return int(pyopencl.array.max(self.tree.box_target_counts_nonchild,
                 queue).get())
 
     # }}}
@@ -682,8 +688,8 @@ class SumpyExpansionWrangler(ExpansionWranglerInterface):
                 source_box_lists=source_box_lists,
                 strength=src_weight_vecs,
                 result=pot,
-                max_npoints_in_one_box=max(self.get_max_nsources_in_one_box(queue),
-                    self.get_max_ntargets_in_one_box(queue)),
+                max_npoints_in_one_box=max(self.max_nsources_in_one_box,
+                    self.max_ntargets_in_one_box),
                 **kwargs)
         events.append(evt)