diff --git a/src/plumpy/communications.py b/src/plumpy/communications.py
index f4941d0f..01bac433 100644
--- a/src/plumpy/communications.py
+++ b/src/plumpy/communications.py
@@ -81,7 +81,7 @@ def convert_to_comm(
         def _passthrough(*args: Any, **kwargs: Any) -> bool:
             sender = kwargs.get('sender', args[1])
             subject = kwargs.get('subject', args[2])
-            return callback.is_filtered(sender, subject)  # type: ignore[attr-defined]
+            return callback.is_filtered(sender, subject)
     else:
 
         def _passthrough(*args: Any, **kwargs: Any) -> bool:  # pylint: disable=unused-argument
diff --git a/src/plumpy/lang.py b/src/plumpy/lang.py
index aad2abb6..450927d6 100644
--- a/src/plumpy/lang.py
+++ b/src/plumpy/lang.py
@@ -31,7 +31,7 @@ def wrapped_fn(self: Any, *args: Any, **kwargs: Any) -> Callable[..., Any]:
 
                 return func(self, *args, **kwargs)
         else:
-            wrapped_fn = func
+            wrapped_fn = func  # type: ignore[assignment]
 
         return wrapped_fn
 
@@ -60,7 +60,7 @@ def wrapped_fn(self: Any, *args: Any, **kwargs: Any) -> Callable[..., Any]:
 
                 return func(self, *args, **kwargs)
         else:
-            wrapped_fn = func
+            wrapped_fn = func  # type: ignore[assignment]
 
         return wrapped_fn
 
diff --git a/src/plumpy/workchains.py b/src/plumpy/workchains.py
index 60208c09..b7690c82 100644
--- a/src/plumpy/workchains.py
+++ b/src/plumpy/workchains.py
@@ -1,11 +1,27 @@
 # -*- coding: utf-8 -*-
+from __future__ import annotations
+
 import abc
 import asyncio
 import collections
 import inspect
 import logging
 import re
-from typing import Any, Callable, Dict, Hashable, List, Mapping, Optional, Sequence, Tuple, Type, Union, cast
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    Hashable,
+    List,
+    Mapping,
+    MutableSequence,
+    Optional,
+    Sequence,
+    Tuple,
+    Type,
+    Union,
+    cast,
+)
 
 import kiwipy
 
@@ -327,7 +343,7 @@ class _Block(_Instruction, collections.abc.Sequence):
 
     def __init__(self, instructions: Sequence[Union[_Instruction, WC_COMMAND_TYPE]]) -> None:
         # Build up the list of commands
-        comms = []
+        comms: MutableSequence[_Instruction | _FunctionCall] = []
         for instruction in instructions:
             if not isinstance(instruction, _Instruction):
                 # Assume it's a function call
@@ -335,7 +351,7 @@ def __init__(self, instructions: Sequence[Union[_Instruction, WC_COMMAND_TYPE]])
             else:
                 comms.append(instruction)
 
-        self._instruction: List[Union[_Instruction, _FunctionCall]] = comms
+        self._instruction: MutableSequence[_Instruction | _FunctionCall] = comms
 
     def __getitem__(self, index: int) -> Union[_Instruction, _FunctionCall]:  # type: ignore
         return self._instruction[index]