diff --git a/docs/how_it_works.md b/docs/how_it_works.md
index 484da0a..ffff311 100644
--- a/docs/how_it_works.md
+++ b/docs/how_it_works.md
@@ -132,6 +132,11 @@ text and children elements within a node. When using
 [`Document.to_xml`](api/document.md#xml2db.document.Document.to_xml), text value will always appear before children 
 elements.
 
+#### Wildcards
+
+Wildcards (`xs:any` elements and `xs:anyAttribute` attributes) allow content that the schema does not describe. Schemas
+containing them are accepted, but the matching content is not imported and a warning is logged.
+
 ## Loading process
 
 This section explains in detail how parsing and loading work. Loading an XML file breaks down into the following steps.
diff --git a/src/xml2db/model.py b/src/xml2db/model.py
index 049fd6a..e5a30b0 100644
--- a/src/xml2db/model.py
+++ b/src/xml2db/model.py
@@ -428,6 +428,11 @@ def get_occurs(particle):
         # go through item attributes and add them as columns, adding a suffix if an element with the same name exists
         children_names = None
         for attrib_name, attrib in parent_node.attributes.items():
+            if attrib_name is None:
+                logger.warning(
+                    f"type '{parent_type}' contains a xsd:anyAttribute, which is ignored"
+                )
+                continue
             if children_names is None:
                 children_names = [child.local_name for child in parent_node]
             (
diff --git a/tests/sample_models/orders/equivalent_xml/order1a.xml b/tests/sample_models/orders/equivalent_xml/order1a.xml
index 82234d8..788b944 100644
--- a/tests/sample_models/orders/equivalent_xml/order1a.xml
+++ b/tests/sample_models/orders/equivalent_xml/order1a.xml
@@ -13,7 +13,7 @@
       <companyId>
         <bic>JIDAZIO786DAZH</bic>
       </companyId>
-      <extra>
+      <extra source="crm">
         <profileName>profile 1</profileName>
       </extra>
     </orderperson>
diff --git a/tests/sample_models/orders/orders.xsd b/tests/sample_models/orders/orders.xsd
index beb0724..451f176 100644
--- a/tests/sample_models/orders/orders.xsd
+++ b/tests/sample_models/orders/orders.xsd
@@ -23,6 +23,7 @@
         <xs:sequence>
             <xs:any minOccurs="0" maxOccurs="unbounded" processContents="skip" />
         </xs:sequence>
+        <xs:anyAttribute processContents="skip" />
     </xs:complexType>
 
     <xs:complexType name="contacttype">