diff --git a/canopen/node/base.py b/canopen/node/base.py
index 45ad35b4..80129e7a 100644
--- a/canopen/node/base.py
+++ b/canopen/node/base.py
@@ -1,4 +1,4 @@
-from typing import TextIO, Union
+from typing import Optional, TextIO, Union
 
 import canopen.network
 from canopen.objectdictionary import ObjectDictionary, import_od
@@ -25,7 +25,7 @@ def __init__(
             object_dictionary = import_od(object_dictionary, node_id)
         self.object_dictionary = object_dictionary
 
-        self.id = node_id or self.object_dictionary.node_id
+        self.id: Optional[int] = node_id or self.object_dictionary.node_id
 
     def has_network(self) -> bool:
         """Check whether the node has been associated to a network."""
diff --git a/canopen/node/local.py b/canopen/node/local.py
index 886d8ac8..f91b8b20 100644
--- a/canopen/node/local.py
+++ b/canopen/node/local.py
@@ -24,6 +24,8 @@ def __init__(
         object_dictionary: Union[ObjectDictionary, str],
     ):
         super(LocalNode, self).__init__(node_id, object_dictionary)
+        assert self.id is not None, "node_id must be specified"
+        self.id: int
 
         self.data_store: dict[int, dict[int, bytes]] = {}
         self._read_callbacks = []
diff --git a/canopen/node/remote.py b/canopen/node/remote.py
index 371f784c..4e6869ea 100644
--- a/canopen/node/remote.py
+++ b/canopen/node/remote.py
@@ -35,6 +35,8 @@ def __init__(
         load_od: bool = False,
     ):
         super(RemoteNode, self).__init__(node_id, object_dictionary)
+        assert self.id is not None, "node_id must be specified"
+        self.id: int
 
         #: Enable WORKAROUND for reversed PDO mapping entries
         self.curtis_hack = False
diff --git a/canopen/pdo/base.py b/canopen/pdo/base.py
index 96ad057a..c39b5c4f 100644
--- a/canopen/pdo/base.py
+++ b/canopen/pdo/base.py
@@ -592,7 +592,7 @@ def remote_request(self) -> None:
         if self.enabled and self.rtr_allowed and self.cob_id:
             self.pdo_node.network.send_message(self.cob_id, bytes(), remote=True)
 
-    def wait_for_reception(self, timeout: float = 10) -> float:
+    def wait_for_reception(self, timeout: float = 10) -> Optional[float]:
         """Wait for the next transmit PDO.
 
         :param float timeout: Max time to wait in seconds.
@@ -620,6 +620,8 @@ def get_data(self) -> bytes:
 
         :return: PdoVariable value as :class:`bytes`.
         """
+        assert self.offset is not None, "PdoVariable offset not set"
+        assert self.pdo_parent is not None, "PdoVariable has no parent map"
         byte_offset, bit_offset = divmod(self.offset, 8)
 
         if bit_offset or self.length % 8:
@@ -647,6 +649,8 @@ def set_data(self, data: bytes):
 
         :param data: Value for the PDO variable in the PDO message.
         """
+        assert self.offset is not None, "PdoVariable offset not set"
+        assert self.pdo_parent is not None, "PdoVariable has no parent map"
         byte_offset, bit_offset = divmod(self.offset, 8)
         logger.debug("Updating %s to %s in %s",
                      self.name, binascii.hexlify(data), self.pdo_parent.name)