diff --git a/cdr_schemas/prospectivity_input.py b/cdr_schemas/prospectivity_input.py
index 17d4cdd..59205b5 100644
--- a/cdr_schemas/prospectivity_input.py
+++ b/cdr_schemas/prospectivity_input.py
@@ -92,7 +92,7 @@ class CreateCriticalMineralAssessment(BaseModel):
     description: str
 
 
-TranformMethods = List[Union[TransformMethod, Impute, ScalingType]]
+TranformMethods = List[Union[TransformMethod, Impute, ScalingType, str]]
 
 
 # MTRI UI TO CDR: