diff --git a/requirements.txt b/requirements.txt
index 6690e3d9651bad06a8fd28e444167fe03bbb119f..c4425ea87f856d9ab34d4101d3917788e13b6aeb 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,6 +3,6 @@ sympy==1.0
 git+https://github.com/inducer/pymbolic
 git+https://github.com/inducer/islpy
 git+https://github.com/inducer/pyopencl
-git+https://github.com/inducer/boxtree
+git+https://gitlab.tiker.net/inducer/boxtree@compress-list-3-new
 git+https://github.com/inducer/loopy
 git+https://github.com/inducer/pyfmmlib
diff --git a/sumpy/fmm.py b/sumpy/fmm.py
index 36b073779498a5768e72ebc4e85a66b4b061e9b4..d21ee06a55b49c5f1ceb547776823fb5d082a48c 100644
--- a/sumpy/fmm.py
+++ b/sumpy/fmm.py
@@ -450,7 +450,7 @@ class SumpyExpansionWrangler(object):
 
     def eval_multipoles(self,
             level_start_target_box_nrs,
-            target_boxes, source_boxes_by_level, mpole_exps):
+            target_boxes_by_source_level, source_boxes_by_level, mpole_exps):
         pot = self.output_zeros()
 
         kwargs = self.kernel_extra_kwargs.copy()
@@ -459,7 +459,7 @@ class SumpyExpansionWrangler(object):
         wait_for = mpole_exps.events
 
         for isrc_level, ssn in enumerate(source_boxes_by_level):
-            if len(target_boxes) == 0:
+            if len(target_boxes_by_source_level[isrc_level]) == 0:
                 continue
 
             m2p = self.code.m2p(self.level_orders[isrc_level])
@@ -473,7 +473,7 @@ class SumpyExpansionWrangler(object):
                     src_expansions=source_mpoles_view,
                     src_base_ibox=source_level_start_ibox,
 
-                    target_boxes=target_boxes,
+                    target_boxes=target_boxes_by_source_level[isrc_level],
                     source_box_starts=ssn.starts,
                     source_box_lists=ssn.lists,
                     centers=self.tree.box_centers,