diff --git a/whispering/schema.py b/whispering/schema.py
index c3c12ac..16e8501 100644
--- a/whispering/schema.py
+++ b/whispering/schema.py
@@ -48,7 +48,7 @@ class Context(BaseModel, arbitrary_types_allowed=True):
     vad_threshold: float
     max_nospeech_skip: int
 
-    data_type: Optional[str] = "float32"
+    data_type: str = "float32"
 
 
 class ParsedChunk(BaseModel):