diff --git a/src/subscript/sunsch/sunsch.py b/src/subscript/sunsch/sunsch.py
index 8e4258a74..1af903068 100755
--- a/src/subscript/sunsch/sunsch.py
+++ b/src/subscript/sunsch/sunsch.py
@@ -65,9 +65,8 @@ class SunschConfig(BaseModel):
     ] = None
     insert: Optional[List[InsertStatement]] = None
 
-    @model_validator(mode="before")
-    @classmethod
-    def set_date_defaults(cls, config: Any) -> Any:
+    def __init__(self, **config):
+        """Transform the input to provide defaults to required fields"""
         if "startdate" not in config:
             if "starttime" in config:
                 config["startdate"] = config["starttime"]
@@ -82,7 +81,7 @@ def set_date_defaults(cls, config: Any) -> Any:
         if "refdate" not in config:
             config["refdate"] = config["startdate"]
 
-        return config
+        super().__init__(**config)
 
 
 def datetime_from_date(