diff --git a/grudge/symbolic/compiler.py b/grudge/symbolic/compiler.py
index b82442390fbce4763fe5352886f4869d69f37617..d4fe781e0607b74b2b5961508f28eac4bbd8eedc 100644
--- a/grudge/symbolic/compiler.py
+++ b/grudge/symbolic/compiler.py
@@ -43,7 +43,6 @@ from loopy.version import LOOPY_USE_LANGUAGE_VERSION_2018_1  # noqa: F401
 # {{{ instructions
 
 class Instruction(Record):
-    __slots__ = []
     priority = 0
     neglect_for_dofdesc_inference = False
 
diff --git a/grudge/symbolic/operators.py b/grudge/symbolic/operators.py
index 9813b648c8ef308ff06a1e6db189b581a30e30d9..babccafa211160414358e9617a7996eb22a61bed 100644
--- a/grudge/symbolic/operators.py
+++ b/grudge/symbolic/operators.py
@@ -27,6 +27,8 @@ from six.moves import intern
 import numpy as np
 import pymbolic.primitives
 
+from typing import Tuple
+
 __doc__ = """
 
 Building blocks and mappers for operator expression trees.
@@ -131,7 +133,7 @@ class Operator(pymbolic.primitives.Expression):
                 dd_in=dd_in or self.dd_in,
                 dd_out=dd_out or self.dd_out)
 
-    init_arg_names = ("dd_in", "dd_out")
+    init_arg_names: Tuple[str, ...] = ("dd_in", "dd_out")
 
     def __getinitargs__(self):
         return (self.dd_in, self.dd_out,)