diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a8db56a6..7d650010 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -48,7 +48,7 @@ jobs:
     strategy:
       max-parallel: 5
       matrix:
-        python: [3.9, "3.10", "3.11", "3.12", "3.13"]
+        python: [3.9, "3.10", "3.11", "3.12", "3.13", "3.14"]
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@v2
diff --git a/arroyo/backends/kafka/consumer.py b/arroyo/backends/kafka/consumer.py
index c6b2e1a4..17574a03 100644
--- a/arroyo/backends/kafka/consumer.py
+++ b/arroyo/backends/kafka/consumer.py
@@ -346,7 +346,7 @@ def assignment_callback(
             try:
                 assignment: MutableSequence[ConfluentTopicPartition] = []
 
-                for partition in self.__consumer.committed(partitions):
+                for partition in self.__consumer.committed(list(partitions)):
                     if partition.offset >= 0:
                         assignment.append(partition)
                     elif partition.offset == OFFSET_INVALID:
@@ -364,7 +364,7 @@ def assignment_callback(
 
                 # Ensure that all partitions are resumed on assignment to avoid
                 # carrying over state from a previous assignment.
-                self.resume([p for p in offsets])
+                self.resume(list(offsets.keys()))
 
             except Exception:
                 self.__state = KafkaConsumerState.ERROR
@@ -382,13 +382,15 @@ def revocation_callback(
         ) -> None:
             self.__state = KafkaConsumerState.REVOKING
 
-            partitions = [Partition(Topic(i.topic), i.partition) for i in partitions]
+            revoked_partitions = [
+                Partition(Topic(i.topic), i.partition) for i in partitions
+            ]
 
             try:
                 if on_revoke is not None:
-                    on_revoke(partitions)
+                    on_revoke(revoked_partitions)
             finally:
-                for partition in partitions:
+                for partition in revoked_partitions:
                     # Staged offsets are deleted during partition revocation to
                     # prevent later committing offsets for partitions that are
                     # no longer owned by this consumer.
@@ -476,8 +478,11 @@ def poll(
             code = error.code()
             if code == KafkaError._PARTITION_EOF:
                 raise EndOfPartition(
-                    Partition(Topic(message.topic()), message.partition()),
-                    message.offset(),
+                    Partition(
+                        Topic(cast(str, message.topic())),
+                        cast(int, message.partition()),
+                    ),
+                    cast(int, message.offset()),
                 )
             elif code == KafkaError._TRANSPORT:
                 raise TransportError(str(error))
@@ -489,15 +494,33 @@ def poll(
             else:
                 raise ConsumerError(str(error))
 
-        headers: Optional[Headers] = message.headers()
+        raw_headers = message.headers()
+        if raw_headers is None:
+            headers = []
+        elif isinstance(raw_headers, dict):
+            headers = [
+                (k, v if isinstance(v, bytes) else b"")
+                for k, v in raw_headers.items()
+            ]
+        else:
+            headers = [
+                (k, v if isinstance(v, bytes) else b"")
+                for k, v in raw_headers
+            ]
+        value = message.value()
+        if value is None:
+            value = b""
         broker_value = BrokerValue(
             KafkaPayload(
                 message.key(),
-                message.value(),
-                headers if headers is not None else [],
+                value,
+                headers,
+            ),
+            Partition(
+                Topic(cast(str, message.topic())),
+                cast(int, message.partition()),
             ),
-            Partition(Topic(message.topic()), message.partition()),
-            message.offset(),
+            cast(int, message.offset()),
             datetime.utcfromtimestamp(message.timestamp()[1] / 1000.0),
         )
         self.__offsets[broker_value.partition] = broker_value.next_offset
@@ -737,8 +760,8 @@ class KafkaProducer(Producer[KafkaPayload]):
     def __init__(
         self, configuration: Mapping[str, Any], use_simple_futures: bool = False
     ) -> None:
-        self.__configuration = configuration
-        self.__producer = ConfluentKafkaProducer(configuration)
+        self.__configuration = dict(configuration)
+        self.__producer = ConfluentKafkaProducer(self.__configuration)
         self.__shutdown_requested = Event()
 
         # The worker must execute in a separate thread to ensure that callbacks
@@ -778,8 +801,11 @@ def __delivery_callback(
                 future.set_result(
                     BrokerValue(
                         payload,
-                        Partition(Topic(message.topic()), message.partition()),
-                        message.offset(),
+                        Partition(
+                            Topic(cast(str, message.topic())),
+                            cast(int, message.partition()),
+                        ),
+                        cast(int, message.offset()),
                         datetime.utcfromtimestamp(timestamp_value / 1000.0),
                     ),
                 )
@@ -815,7 +841,7 @@ def produce(
         produce(
             value=payload.value,
             key=payload.key,
-            headers=payload.headers,
+            headers=cast(Any, payload.headers),
             on_delivery=partial(self.__delivery_callback, future, payload),
         )
         return future
@@ -832,14 +858,15 @@ def close(self) -> Future[None]:
 METRICS_FREQUENCY_SEC = 1.0
 
 
-class ConfluentProducer(ConfluentKafkaProducer):  # type: ignore[misc]
+class ConfluentProducer(ConfluentKafkaProducer):
     """
     A thin wrapper for confluent_kafka.Producer that adds metrics reporting.
     """
 
     def __init__(self, configuration: Mapping[str, Any]) -> None:
-        super().__init__(configuration)
-        self.producer_name = configuration.get("client.id") or None
+        config_dict = dict(configuration)
+        super().__init__(config_dict)
+        self.producer_name = config_dict.get("client.id") or None
         self.__metrics = get_metrics()
         self.__produce_counters: MutableMapping[str, int] = defaultdict(int)
         self.__reset_metrics()
@@ -873,7 +900,7 @@ def produce(self, *args: Any, **kwargs: Any) -> None:
         on_delivery = kwargs.pop("on_delivery", None)
         user_callback = callback or on_delivery
         wrapped_callback = self.__delivery_callback(user_callback)
-        super().produce(*args, on_delivery=wrapped_callback, **kwargs)
+        super().produce(*args, on_delivery=wrapped_callback, **kwargs)  # type: ignore[misc]
 
     def __flush_metrics(self) -> None:
         for status, count in self.__produce_counters.items():
@@ -890,7 +917,7 @@ def __flush_metrics(self) -> None:
     def flush(self, timeout: float = -1) -> int:
         # Kafka producer flush should flush metrics too
         self.__flush_metrics()
-        return cast(int, super().flush(timeout))
+        return super().flush(timeout)
 
     def __reset_metrics(self) -> None:
         self.__produce_counters.clear()
diff --git a/arroyo/backends/local/backend.py b/arroyo/backends/local/backend.py
index 760f7f22..d845b9a5 100644
--- a/arroyo/backends/local/backend.py
+++ b/arroyo/backends/local/backend.py
@@ -216,10 +216,12 @@ def unsubscribe(self) -> None:
             if self.__closed:
                 raise RuntimeError("consumer is closed")
 
+            subscription = self.__subscription
+            assert subscription is not None
             self.__pending_callbacks.append(
                 partial(
                     self.__revoke,
-                    self.__subscription,
+                    subscription,
                     self.__broker.unsubscribe(self),
                 )
             )
diff --git a/arroyo/processing/strategies/run_task_with_multiprocessing.py b/arroyo/processing/strategies/run_task_with_multiprocessing.py
index f3e3ffae..0ee408e0 100644
--- a/arroyo/processing/strategies/run_task_with_multiprocessing.py
+++ b/arroyo/processing/strategies/run_task_with_multiprocessing.py
@@ -111,12 +111,15 @@ def __getitem__(self, index: int) -> TBatchValue:
         # was still "alive" in a different part of the processing pipeline, the
         # contents of the message would be liable to be corrupted (at best --
         # possibly causing a data leak/security issue at worst.)
+        buf = self.block.buf
+        if buf is None:
+            raise RuntimeError("shared memory block has no buffer")
         return cast(
             TBatchValue,
             pickle.loads(
                 data,
                 buffers=[
-                    self.block.buf[offset : offset + length].tobytes()
+                    buf[offset : offset + length].tobytes()
                     for offset, length in buffers
                 ],
             ),
@@ -159,7 +162,10 @@ def buffer_callback(buffer: PickleBuffer) -> None:
                     f"Value exceeds available space in block, {length} "
                     f"bytes needed but {self.block.size - offset} bytes free."
                 )
-            self.block.buf[offset : offset + length] = value
+            buf = self.block.buf
+            if buf is None:
+                raise RuntimeError("shared memory block has no buffer")
+            buf[offset : offset + length] = value
             self.__offset += length
             buffers.append((offset, length))
 
diff --git a/requirements-test.txt b/requirements-test.txt
index 1327328a..9ad8d9ed 100644
--- a/requirements-test.txt
+++ b/requirements-test.txt
@@ -1,3 +1,3 @@
 pytest==8.4.1
 pytest-benchmark==4.0.0
-mypy==0.961
+mypy>=1.19.1
diff --git a/requirements.txt b/requirements.txt
index 7e4f7dfd..a958b727 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1 @@
-confluent-kafka>=2.11.0,<2.12.0
+confluent-kafka>=2.12.1
diff --git a/tests/backends/test_confluent_producer.py b/tests/backends/test_confluent_producer.py
index 96b5783d..e10983ee 100644
--- a/tests/backends/test_confluent_producer.py
+++ b/tests/backends/test_confluent_producer.py
@@ -28,7 +28,9 @@ def test_metrics_callback_records_success(self) -> None:
             {"bootstrap.servers": "fake:9092", "client.id": "test-producer-name"}
         )
         mock_message = mock.Mock(spec=ConfluentMessage)
-        producer._ConfluentProducer__metrics_delivery_callback(None, mock_message)
+        getattr(
+            producer, "_ConfluentProducer__metrics_delivery_callback"
+        )(None, mock_message)
         producer.flush()  # Flush buffered metrics
         assert (
             Increment(
@@ -44,7 +46,9 @@ def test_metrics_callback_records_error(self) -> None:
         producer = ConfluentProducer({"bootstrap.servers": "fake:9092"})
         mock_error = mock.Mock(spec=KafkaError)
         mock_message = mock.Mock(spec=ConfluentMessage)
-        producer._ConfluentProducer__metrics_delivery_callback(mock_error, mock_message)
+        getattr(
+            producer, "_ConfluentProducer__metrics_delivery_callback"
+        )(mock_error, mock_message)
         producer.flush()  # Flush buffered metrics
         assert (
             Increment("arroyo.producer.produce_status", 1, {"status": "error"})
@@ -63,7 +67,9 @@ def user_callback(
         ) -> None:
             user_callback_invoked.append((error, message))
 
-        wrapped = producer._ConfluentProducer__delivery_callback(user_callback)
+        wrapped = getattr(
+            producer, "_ConfluentProducer__delivery_callback"
+        )(user_callback)
         mock_message = mock.Mock(spec=ConfluentMessage)
         wrapped(None, mock_message)
         producer.flush()  # Flush buffered metrics
diff --git a/tests/backends/test_kafka.py b/tests/backends/test_kafka.py
index 7fba26dd..e222cfc4 100644
--- a/tests/backends/test_kafka.py
+++ b/tests/backends/test_kafka.py
@@ -10,7 +10,7 @@
 from unittest import mock
 
 import pytest
-from confluent_kafka.admin import AdminClient, NewTopic
+from confluent_kafka.admin import AdminClient, NewTopic  # type: ignore[attr-defined]
 
 from arroyo.backends.kafka import KafkaConsumer, KafkaPayload, KafkaProducer
 from arroyo.backends.kafka.commit import CommitCodec
diff --git a/tests/processing/strategies/test_filter.py b/tests/processing/strategies/test_filter.py
index f3268f47..bc903833 100644
--- a/tests/processing/strategies/test_filter.py
+++ b/tests/processing/strategies/test_filter.py
@@ -170,7 +170,7 @@ def test_function(message: Message[bool]) -> bool:
 def test_backpressure_in_join() -> None:
     topic = Topic("topic")
     next_step = Mock()
-    next_step.submit.side_effect = [None] * 6 + [MessageRejected]  # type: ignore
+    next_step.submit.side_effect = [None] * 6 + [MessageRejected]
 
     now = datetime.now()
 
diff --git a/tests/test_kip848_e2e.py b/tests/test_kip848_e2e.py
index 63f8b983..532d0e91 100644
--- a/tests/test_kip848_e2e.py
+++ b/tests/test_kip848_e2e.py
@@ -6,7 +6,7 @@
 from contextlib import closing
 from typing import Any, Iterator, Mapping
 
-from confluent_kafka.admin import AdminClient, NewTopic
+from confluent_kafka.admin import AdminClient, NewTopic  # type: ignore[attr-defined]
 
 from arroyo.backends.kafka import KafkaProducer
 from arroyo.backends.kafka.configuration import build_kafka_consumer_configuration