diff --git a/python/ray/autoscaler/_private/load_metrics.py b/python/ray/autoscaler/_private/load_metrics.py
index 4d7463703..9d1799308 100644
--- a/python/ray/autoscaler/_private/load_metrics.py
+++ b/python/ray/autoscaler/_private/load_metrics.py
@@ -32,10 +32,14 @@ class LoadMetrics:
                static_resources,
                dynamic_resources,
                resource_load,
-               waiting_bundles=[],
-               infeasible_bundles=[]):
+               waiting_bundles=None,
+               infeasible_bundles=None):
         self.resource_load_by_ip[ip] = resource_load
         self.static_resources_by_ip[ip] = static_resources
+        if not waiting_bundles:
+            waiting_bundles = []
+        if not infeasible_bundles:
+            infeasible_bundles = []
 
         # We are not guaranteed to have a corresponding dynamic resource for
         # every static resource because dynamic resources are based on the
diff --git a/python/ray/util/placement_group.py b/python/ray/util/placement_group.py
index d908b74ea..b0c346407 100644
--- a/python/ray/util/placement_group.py
+++ b/python/ray/util/placement_group.py
@@ -51,7 +51,7 @@ class PlacementGroup:
         resource_name, value = self._get_none_zero_resource(bundle)
         num_cpus = 0
         num_gpus = 0
-        resources = None
+        resources = {}
         if resource_name == "CPU":
             num_cpus = value
         elif resource_name == "GPU":