diff --git a/asyncua/ua/uatypes.py b/asyncua/ua/uatypes.py
index 0960d15da..00bfb778d 100644
--- a/asyncua/ua/uatypes.py
+++ b/asyncua/ua/uatypes.py
@@ -957,6 +957,7 @@ def __post_init__(self):
                     VariantType.String,
                     VariantType.DateTime,
                     VariantType.ExtensionObject,
+                    VariantType.ByteString,
             ):
                 raise UaError(
                     f"Non array Variant of type {self.VariantType} cannot have value None"