diff --git a/lib/python/ray/serialization.py b/lib/python/ray/serialization.py
index e22bf6604..8b99cdacd 100644
--- a/lib/python/ray/serialization.py
+++ b/lib/python/ray/serialization.py
@@ -47,6 +47,9 @@ def from_primitive(primitive_obj):
     obj.deserialize(primitive_obj[1])
   return obj
 
+def is_arrow_serializable(value):
+  return type(value) == np.ndarray and value.dtype.name in ["int8", "int16", "int32", "int64", "uint8", "uint16", "uint32", "uint64", "float32", "float64"]
+
 def serialize(worker_capsule, obj):
   primitive_obj = to_primitive(obj)
   obj_capsule, contained_objrefs = ray.lib.serialize_object(worker_capsule, primitive_obj) # contained_objrefs is a list of the objrefs contained in obj
diff --git a/lib/python/ray/worker.py b/lib/python/ray/worker.py
index 50f98aa3a..db3522d58 100644
--- a/lib/python/ray/worker.py
+++ b/lib/python/ray/worker.py
@@ -6,7 +6,6 @@ from types import ModuleType
 import typing
 import funcsigs
 import numpy as np
-import pynumbuf
 import colorama
 
 import ray
@@ -46,7 +45,7 @@ class Worker(object):
 
   def put_object(self, objref, value):
     """Put `value` in the local object store with objref `objref`. This assumes that the value for `objref` has not yet been placed in the local object store."""
-    if pynumbuf.serializable(value):
+    if serialization.is_arrow_serializable(value):
       ray.lib.put_arrow(self.handle, objref, value)
     else:
       object_capsule, contained_objrefs = serialization.serialize(self.handle, value) # contained_objrefs is a list of the objrefs contained in object_capsule
diff --git a/setup.sh b/setup.sh
index 3979a1a75..917b8e09c 100755
--- a/setup.sh
+++ b/setup.sh
@@ -41,9 +41,4 @@ fi
 pushd "$ROOT_DIR/thirdparty"
   ./download_thirdparty.sh
   ./build_thirdparty.sh
-  pushd numbuf
-    pushd python
-      sudo python setup.py install
-    popd
-  popd
 popd