diff --git a/src/test/kotlin/com/ecwid/apiclient/v3/rule/nullablepropertyrules/FetchedProductRules.kt b/src/test/kotlin/com/ecwid/apiclient/v3/rule/nullablepropertyrules/FetchedProductRules.kt
index 8cb31a62..1113d8f8 100644
--- a/src/test/kotlin/com/ecwid/apiclient/v3/rule/nullablepropertyrules/FetchedProductRules.kt
+++ b/src/test/kotlin/com/ecwid/apiclient/v3/rule/nullablepropertyrules/FetchedProductRules.kt
@@ -89,7 +89,7 @@ val fetchedProductNullablePropertyRules: List<NullablePropertyRule<*, *>> = list
 	IgnoreNullable(FetchedProduct::tax),
 	IgnoreNullable(FetchedProduct::unlimited),
 	IgnoreNullable(FetchedProduct::url),
-	IgnoreNullable(FetchedProduct::customSlug),
+	AllowNullable(FetchedProduct::customSlug),
 	IgnoreNullable(FetchedProduct::warningLimit),
 	IgnoreNullable(FetchedProduct::weight),
 	IgnoreNullable(FetchedProduct::wholesalePrices),