diff --git a/index.d.ts b/index.d.ts
index 1942c9e..bfe4b97 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -7,7 +7,7 @@ export declare class Pass {
 	public headerFields: Schema.Field[];
 	public primaryFields: Schema.Field[];
 	public secondaryFields: Schema.Field[];
-	public auxiliaryFields: (Schema.Field & { row: number })[];
+	public auxiliaryFields: (Schema.Field & { row?: number })[];
 	public backFields: Schema.Field[];
 
 	/**