diff --git a/gxml/Serializable.vala b/gxml/Serializable.vala
index 5028eba3cb36871309b57fe9f200a1315eb36b6c..edaa570187c3d2b599e9b999a78a03e241cbe7ca 100644
--- a/gxml/Serializable.vala
+++ b/gxml/Serializable.vala
@@ -160,7 +160,7 @@ namespace GXml {
      * This method is called recursivally by {@link serialize} method over all properties
      * to be serialized.
      */
-    public abstract GXml.xNode? serialize_property (GXml.xElement element,
+    public abstract GXml.Node? serialize_property (GXml.Node element,
                                                    GLib.ParamSpec prop)
                                                    throws GLib.Error;
 
diff --git a/gxml/SerializableGeeArrayList.vala b/gxml/SerializableGeeArrayList.vala
index 645fcda0113c43f7a58ea57351e99fd3a983781e..24288d5435d612f18c491569f30198ff73cf4abb 100644
--- a/gxml/SerializableGeeArrayList.vala
+++ b/gxml/SerializableGeeArrayList.vala
@@ -99,13 +99,13 @@ public class GXml.SerializableArrayList<G> : Gee.ArrayList<G>, Serializable, Ser
     }
     return node;
   }
-  public virtual GXml.xNode? serialize_property (GXml.xElement element,
+  public virtual GXml.Node? serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
     return default_serialize_property (element, prop);
   }
-  public GXml.xNode? default_serialize_property (GXml.xElement element,
+  public GXml.Node? default_serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
diff --git a/gxml/SerializableGeeDualKeyMap.vala b/gxml/SerializableGeeDualKeyMap.vala
index eae37d91c779fd8d681e691b395183c5a17135ee..d1d84e3369eb8a7a93739208b04ab5dd35095919 100644
--- a/gxml/SerializableGeeDualKeyMap.vala
+++ b/gxml/SerializableGeeDualKeyMap.vala
@@ -178,13 +178,13 @@ public class GXml.SerializableDualKeyMap<P,S,V> : Object, Serializable, Serializ
     }
     return node;
   }
-  public virtual GXml.xNode? serialize_property (GXml.xElement element,
+  public virtual GXml.Node? serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
     return default_serialize_property (element, prop);
   }
-  public GXml.xNode? default_serialize_property (GXml.xElement element,
+  public GXml.Node? default_serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
diff --git a/gxml/SerializableGeeHashMap.vala b/gxml/SerializableGeeHashMap.vala
index aaba248e01d0f12303a66639a57d046d9c138475..7f53ec7e11e882e45204447189cdb51d757f1e40 100644
--- a/gxml/SerializableGeeHashMap.vala
+++ b/gxml/SerializableGeeHashMap.vala
@@ -95,13 +95,13 @@ public class GXml.SerializableHashMap<K,V> : Gee.HashMap<K,V>, Serializable, Ser
     }
     return node;
   }
-  public virtual GXml.xNode? serialize_property (GXml.xElement element,
+  public virtual GXml.Node? serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
     return default_serialize_property (element, prop);
   }
-  public GXml.xNode? default_serialize_property (GXml.xElement element,
+  public GXml.Node? default_serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
diff --git a/gxml/SerializableGeeTreeMap.vala b/gxml/SerializableGeeTreeMap.vala
index d28f2bd8a54d91ef0a1bb52ecbf7b2940298916d..79f8448e1c83ed55368176e11091b5bfbf6f4d41 100644
--- a/gxml/SerializableGeeTreeMap.vala
+++ b/gxml/SerializableGeeTreeMap.vala
@@ -98,13 +98,13 @@ public class GXml.SerializableTreeMap<K,V> : Gee.TreeMap<K,V>, Serializable, Ser
     }
     return node;
   }
-  public virtual GXml.xNode? serialize_property (GXml.xElement element,
+  public virtual GXml.Node? serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
     return default_serialize_property (element, prop);
   }
-  public GXml.xNode? default_serialize_property (GXml.xElement element,
+  public GXml.Node? default_serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
diff --git a/gxml/SerializableJson.vala b/gxml/SerializableJson.vala
index cbc4d1ba13bff94e8ea13c7b262e08254b0e6498..5eec3e08ad033097e6c794100418bc94d91cc5fd 100644
--- a/gxml/SerializableJson.vala
+++ b/gxml/SerializableJson.vala
@@ -139,10 +139,12 @@ public class GXml.SerializableJson : GLib.Object, GXml.Serializable
     return root;
   }
 
-  public virtual GXml.xNode? serialize_property (xElement element, 
+  public virtual GXml.Node? serialize_property (GXml.Node node, 
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
+                                        requires (node is xElement)
   {
+    xElement element = (xElement) node;
     Type type;
     Value val;
     GXml.xNode value_node = null;
diff --git a/gxml/SerializableObjectModel.vala b/gxml/SerializableObjectModel.vala
index 46691c49354611cabdf955b377c2d8a8e454031b..41d394a56d68fa06234fa7001008580a676b3c3d 100644
--- a/gxml/SerializableObjectModel.vala
+++ b/gxml/SerializableObjectModel.vala
@@ -153,11 +153,13 @@ public abstract class GXml.SerializableObjectModel : Object, Serializable
     return element;
   }
 
-  public virtual GXml.xNode? serialize_property (GXml.xElement element,
+  public virtual GXml.Node? serialize_property (GXml.Node element,
                                         GLib.ParamSpec prop)
                                         throws GLib.Error
   {
-    return default_serialize_property (element, prop);
+    if (element is xElement)
+      return default_serialize_property ((xElement) element, prop);
+    return null;
   }
   public GXml.xNode? default_serialize_property (GXml.xElement element,
                                         GLib.ParamSpec prop)