diff --git a/daisy/serial_server.py b/daisy/serial_server.py
index dc586ac0..b44e01c8 100644
--- a/daisy/serial_server.py
+++ b/daisy/serial_server.py
@@ -1,5 +1,6 @@
 from .block import BlockStatus
 from .scheduler import Scheduler
+from .task import Task
 from .task_state import TaskState
 from .server_observer import ServerObservee
 import logging
@@ -11,14 +12,16 @@ class SerialServer(ServerObservee):
     def __init__(self):
         super().__init__()
 
-    def run_blockwise(self, tasks, scheduler=None) -> dict[str, TaskState]:
+    def run_blockwise(
+        self, tasks: list[Task], scheduler=None
+    ) -> dict[str, TaskState]:
         if scheduler is None:
             scheduler = Scheduler(tasks)
         else:
             scheduler = scheduler
 
         started_tasks = set()
-        finished_tasks = set()
+        finished_tasks: set[str] = set()
         all_tasks = set(task.task_id for task in tasks)
         process_funcs = {task.task_id: task.process_function for task in tasks}
 
@@ -63,3 +66,4 @@ def run_blockwise(self, tasks, scheduler=None) -> dict[str, TaskState]:
             if len(process_funcs) == 0:
                 self.notify_server_exit()
                 return scheduler.task_states
+        raise NotImplementedError("Unreachable")
diff --git a/daisy/server.py b/daisy/server.py
index 7eaf389b..de88e840 100644
--- a/daisy/server.py
+++ b/daisy/server.py
@@ -25,9 +25,7 @@
 
 
 class Server(ServerObservee):
-
     def __init__(self, stop_event=None):
-
         super().__init__()
 
         if stop_event is None:
@@ -41,7 +39,6 @@ def __init__(self, stop_event=None):
         logger.debug("Started server listening at %s:%s", self.hostname, self.port)
 
     def run_blockwise(self, tasks, scheduler=None) -> dict[str, TaskState]:
-
         if scheduler is None:
             self.scheduler = Scheduler(tasks)
         else:
@@ -49,11 +46,13 @@ def run_blockwise(self, tasks, scheduler=None) -> dict[str, TaskState]:
 
         self.worker_pools = TaskWorkerPools(tasks, self)
         self.block_bookkeeper = BlockBookkeeper()
-        self.started_tasks = set()
-        self.finished_tasks = set()
+        self.started_tasks: set[str] = set()
+        self.finished_tasks: set[str] = set()
         self.all_done = False
 
-        self.pending_requests = {task.task_id: Queue() for task in tasks}
+        self.pending_requests: dict[str, Queue] = {
+            task.task_id: Queue() for task in tasks
+        }
 
         self._recruit_workers()
 
@@ -82,7 +81,6 @@ def _event_loop(self):
                 last_time = current_time
 
     def _get_client_message(self):
-
         try:
             message = self.tcp_server.get_message(timeout=0.1)
         except StreamClosedError:
@@ -92,7 +90,6 @@ def _get_client_message(self):
             return message
 
         for task_id, requests in self.pending_requests.items():
-
             if self.pending_requests[task_id].empty():
                 continue
 
@@ -100,14 +97,12 @@ def _get_client_message(self):
             return self.pending_requests[task_id].get()
 
     def _send_client_message(self, stream, message):
-
         try:
             stream.send_message(message)
         except StreamClosedError:
             pass
 
     def _handle_client_messages(self):
-
         message = self._get_client_message()
 
         if message is None:
@@ -116,7 +111,6 @@ def _handle_client_messages(self):
         self._handle_client_message(message)
 
     def _handle_client_message(self, message):
-
         if isinstance(message, AcquireBlock):
             self._handle_acquire_block(message)
         elif isinstance(message, ReleaseBlock):
@@ -129,7 +123,6 @@ def _handle_client_message(self, message):
         self._check_all_tasks_completed()
 
     def _handle_acquire_block(self, message):
-
         logger.debug("Received block request for task %s", message.task_id)
 
         task_state = self.scheduler.task_states[message.task_id]
@@ -139,11 +132,9 @@ def _handle_acquire_block(self, message):
         block = self.scheduler.acquire_block(message.task_id)
 
         if block is None:
-
             assert task_state.ready_count == 0
 
             if task_state.pending_count == 0:
-
                 logger.debug(
                     "No more pending blocks for task %s, terminating " "client",
                     message.task_id,
@@ -168,7 +159,6 @@ def _handle_acquire_block(self, message):
             self.pending_requests[message.task_id].put(message)
 
         else:
-
             try:
                 logger.debug("Sending block %s to client", block)
                 self._send_client_message(message.stream, SendBlock(block))
@@ -178,7 +168,6 @@ def _handle_acquire_block(self, message):
             self.notify_acquire_block(message.task_id, task_state)
 
     def _handle_release_block(self, message):
-
         logger.debug("Client releases block %s", message.block)
         self._safe_release_block(message.block, message.stream)
 
@@ -232,9 +221,7 @@ def _safe_release_block(self, block, stream):
             )
 
     def _handle_client_exception(self, message):
-
         if isinstance(message, BlockFailed):
-
             logger.error(
                 "Block %s failed in worker %s with %s",
                 message.block,
@@ -252,7 +239,6 @@ def _handle_client_exception(self, message):
             raise message.exception
 
     def _recruit_workers(self):
-
         ready_tasks = self.scheduler.get_ready_tasks()
         ready_tasks = {task.task_id: task for task in ready_tasks}
 
@@ -273,12 +259,10 @@ def _recruit_workers(self):
         self.worker_pools.recruit_workers(ready_tasks)
 
     def _check_for_lost_blocks(self):
-
         lost_blocks = self.block_bookkeeper.get_lost_blocks()
 
         # mark as failed and release the lost blocks
         for block in lost_blocks:
-
             logger.error("Block %s was lost, returning it to scheduler", block)
             block.status = BlockStatus.FAILED
             self._release_block(block)