diff --git a/src/pytypes/onefuzztypes/requests.py b/src/pytypes/onefuzztypes/requests.py
index 39c5922de..ede719479 100644
--- a/src/pytypes/onefuzztypes/requests.py
+++ b/src/pytypes/onefuzztypes/requests.py
@@ -176,7 +176,7 @@ class ScalesetCreate(BaseRequest):
     region: Optional[Region]
     size: int
     spot_instances: bool
-    ephemeral_os_disks: bool
+    ephemeral_os_disks: bool = Field(default=False)
     tags: Dict[str, str]
 
     @validator("size", allow_reuse=True)