diff --git a/src/subscript/check_swatinit/check_swatinit.py b/src/subscript/check_swatinit/check_swatinit.py
index 5baf0e0aa..57cb2ef8a 100644
--- a/src/subscript/check_swatinit/check_swatinit.py
+++ b/src/subscript/check_swatinit/check_swatinit.py
@@ -2,7 +2,7 @@
 
 import argparse
 import sys
-from typing import Any, Dict, List
+from typing import Any, Dict, List, Union
 
 import numpy as np
 import pandas as pd
@@ -473,7 +473,7 @@ def _evaluate_pc(
     swats: List[float],
     scale_vert: List[float],
     swls: List[float],
-    swus: List[float],
+    swus: Union[None, List[float]],
     satfunc: pd.DataFrame,
     sat_name: str = "SW",
     pc_name: str = "PCOW",