diff --git a/spacy/schemas.py b/spacy/schemas.py
index 2268bf100..3b6313db8 100644
--- a/spacy/schemas.py
+++ b/spacy/schemas.py
@@ -119,6 +119,7 @@ class TokenPattern(BaseModel):
     is_currency: Optional[StrictBool] = None
     is_stop: Optional[StrictBool] = None
     is_sent_start: Optional[StrictBool] = None
+    sent_start: Optional[StrictBool] = None
     like_num: Optional[StrictBool] = None
     like_url: Optional[StrictBool] = None
     like_email: Optional[StrictBool] = None