diff --git a/hathor/event/model/event_data.py b/hathor/event/model/event_data.py
index cf22fa424b..632d124a7d 100644
--- a/hathor/event/model/event_data.py
+++ b/hathor/event/model/event_data.py
@@ -101,7 +101,7 @@ class TxData(BaseEventData, extra=Extra.ignore):
     hash: str
     nonce: Optional[int] = None
     timestamp: int
-    signal_bits: int
+    signal_bits: int | None
     version: int
     weight: float
     inputs: list['TxInput']