diff --git a/xmpp-vala/src/module/iq/module.vala b/xmpp-vala/src/module/iq/module.vala
index 47f6e764..abcc271c 100644
--- a/xmpp-vala/src/module/iq/module.vala
+++ b/xmpp-vala/src/module/iq/module.vala
@@ -67,7 +67,7 @@ namespace Xmpp.Iq {
                         }
                     }
                 } else {
-                    Iq.Stanza unavailable_error = new Iq.Stanza.error(iq, new StanzaNode.build("service-unavailable", "urn:ietf:params:xml:ns:xmpp-stanzas").add_self_xmlns());
+                    Iq.Stanza unavailable_error = new Iq.Stanza.error(iq, new ErrorStanza.service_unavailable());
                     send_iq(stream, unavailable_error);
                 }
             }
diff --git a/xmpp-vala/src/module/iq/stanza.vala b/xmpp-vala/src/module/iq/stanza.vala
index 3c938883..825d6a5d 100644
--- a/xmpp-vala/src/module/iq/stanza.vala
+++ b/xmpp-vala/src/module/iq/stanza.vala
@@ -30,17 +30,14 @@ public class Stanza : Xmpp.Stanza {
 
     public Stanza.set(StanzaNode stanza_node, string? id = null) {
         this(id);
-        type_ = TYPE_SET;
+        this.type_ = TYPE_SET;
         stanza.put_node(stanza_node);
     }
 
-    public Stanza.error(Stanza request, StanzaNode error_stanza, StanzaNode? associated_child = null) {
+    public Stanza.error(Stanza request, ErrorStanza error_stanza) {
         this(request.id);
         this.type_ = TYPE_ERROR;
-        stanza.put_node(error_stanza);
-        if (associated_child != null) {
-            stanza.put_node(associated_child);
-        }
+        stanza.put_node(error_stanza.error_node);
     }
     public Stanza.from_stanza(StanzaNode stanza_node, Jid? my_jid) {
         base.incoming(stanza_node, my_jid);
diff --git a/xmpp-vala/src/module/stanza_error.vala b/xmpp-vala/src/module/stanza_error.vala
index c45ff4e3..651e8d2b 100644
--- a/xmpp-vala/src/module/stanza_error.vala
+++ b/xmpp-vala/src/module/stanza_error.vala
@@ -2,6 +2,8 @@ using Gee;
 
 namespace Xmpp {
 
+    private const string ERROR_NS_URI = "urn:ietf:params:xml:ns:xmpp-stanzas";
+
     public class ErrorStanza {
         public const string CONDITION_BAD_REQUEST = "bad-request";
         public const string CONDITION_CONFLICT = "conflict";
@@ -37,14 +39,14 @@ namespace Xmpp {
         }
 
         public string? text {
-            get { return error_node.get_deep_string_content("urn:ietf:params:xml:ns:xmpp-stanzas:text"); }
+            get { return error_node.get_deep_string_content(ERROR_NS_URI + ":text"); }
         }
 
         public string condition {
             get {
                 Gee.List<StanzaNode> subnodes = error_node.sub_nodes;
                 foreach (StanzaNode subnode in subnodes) { // TODO get subnode by ns
-                    if (subnode.ns_uri == "urn:ietf:params:xml:ns:xmpp-stanzas") {
+                    if (subnode.ns_uri == ERROR_NS_URI) {
                         return subnode.name;
                     }
                 }
@@ -52,20 +54,45 @@ namespace Xmpp {
             }
         }
 
-        public string? original_id {
-            get { return stanza.get_attribute("id"); }
-        }
-
         public string type_ {
             get { return error_node.get_attribute("type"); }
         }
 
-        public StanzaNode stanza;
         public StanzaNode error_node;
 
         public ErrorStanza.from_stanza(StanzaNode stanza) {
-            this.stanza = stanza;
             error_node = stanza.get_subnode("error");
         }
+
+        public ErrorStanza.build(string type, string condition, string? human_readable, StanzaNode? application_condition) {
+            error_node = new StanzaNode.build("error")
+                .put_attribute("type", type)
+                .put_node(new StanzaNode.build(condition, ERROR_NS_URI).add_self_xmlns());
+            if (application_condition != null) {
+                error_node.put_node(application_condition);
+            }
+            if (human_readable != null) {
+                error_node.put_node(new StanzaNode.build("text", ERROR_NS_URI)
+                    .add_self_xmlns()
+                    .put_attribute("xml:lang", "en")
+                    .put_node(new StanzaNode.text(text))
+                );
+            }
+        }
+        public ErrorStanza.bad_request(string? human_readable = null) {
+            this.build(TYPE_MODIFY, CONDITION_BAD_REQUEST, human_readable, null);
+        }
+        public ErrorStanza.feature_not_implemented(StanzaNode? application_condition = null) {
+            this.build(TYPE_MODIFY, CONDITION_FEATURE_NOT_IMPLEMENTED, null, application_condition);
+        }
+        public ErrorStanza.item_not_found(StanzaNode? application_condition = null) {
+            this.build(TYPE_CANCEL, CONDITION_ITEM_NOT_FOUND, null, application_condition);
+        }
+        public ErrorStanza.not_acceptable(string? human_readable = null) {
+            this.build(TYPE_MODIFY, CONDITION_NOT_ACCEPTABLE, human_readable, null);
+        }
+        public ErrorStanza.service_unavailable() {
+            this.build(TYPE_CANCEL, CONDITION_SERVICE_UNAVAILABLE, null, null);
+        }
     }
 }