diff --git a/src/zeep/xsd/visitor.py b/src/zeep/xsd/visitor.py
index 5aa40f53..4d2d9f0a 100644
--- a/src/zeep/xsd/visitor.py
+++ b/src/zeep/xsd/visitor.py
@@ -195,7 +195,7 @@ def visit_import(self, node, parent):
             raise XMLParseError(
                 "The attribute 'namespace' must be existent if the "
                 "importing schema has no target namespace.",
-                filename=self.document.location,
+                filename=self.document._location,
                 sourceline=node.sourceline,
             )