diff --git a/public/app/features/transformers/editors/ConvertFieldTypeTransformerEditor.tsx b/public/app/features/transformers/editors/ConvertFieldTypeTransformerEditor.tsx
index 9508dfee1e7..7345c031eac 100644
--- a/public/app/features/transformers/editors/ConvertFieldTypeTransformerEditor.tsx
+++ b/public/app/features/transformers/editors/ConvertFieldTypeTransformerEditor.tsx
@@ -51,7 +51,7 @@ export const ConvertFieldTypeTransformerEditor = ({
 
   const onSelectField = useCallback(
     (idx: number) => (value: string | undefined) => {
-      const conversions = options.conversions;
+      const conversions = [...options.conversions];
       conversions[idx] = { ...conversions[idx], targetField: value ?? '', dateFormat: undefined };
       onChange({
         ...options,