diff --git a/hathor/stratum/stratum.py b/hathor/stratum/stratum.py
index 09bfe41bc..85f69c836 100644
--- a/hathor/stratum/stratum.py
+++ b/hathor/stratum/stratum.py
@@ -122,11 +122,11 @@ class MinerJob(NamedTuple):
     # XXX: these typings are causing too much trouble, since this module hasn't been touched for a while and won't be
     #      touched for the foreseeable future (and will possibly even removed before any changes) it seems fine to just
     #      use Any so there aren't any mypy complaints anymore
-    data: Any = Array('B', 2048)
-    data_size: Any = Value('I')
-    job_id: Any = Array('B', 16)
-    nonce_size: Any = Value('I')
-    weight: Any = Value('d')
+    data: Any
+    data_size: Any
+    job_id: Any
+    nonce_size: Any
+    weight: Any
 
     def update_job(self, params: dict[str, Any]) -> bool:
         """
@@ -836,7 +836,13 @@ class StratumClient(JSONRPC):
     def __init__(self, reactor: Reactor, proc_count: Optional[int] = None, address: Optional[bytes] = None,
                  id_generator: Optional[Callable[[], Iterator[Union[str, int]]]] = lambda: count()):
         self.log = logger.new()
-        self.job_data = MinerJob()
+        self.job_data = MinerJob(
+            data=Array('B', 2048),
+            data_size=Value('I'),
+            job_id=Array('B', 16),
+            nonce_size=Value('I'),
+            weight=Value('d'),
+        )
         self.signal = Value('B')
         self.queue = MQueue()
         self.proc_count = proc_count