diff --git a/parsers/src/ns.rs b/parsers/src/ns.rs
index 5dedc3efc879a0f0c7b09c77bb6af87b247f3656..d5dfe0791a7ee881e8354ead7f06e32bee12069d 100644
--- a/parsers/src/ns.rs
+++ b/parsers/src/ns.rs
@@ -10,6 +10,8 @@ pub const JABBER_CLIENT: &str = "jabber:client";
 /// RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core
 pub const XMPP_STANZAS: &str = "urn:ietf:params:xml:ns:xmpp-stanzas";
 /// RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core
+pub const XMPP_STREAMS: &str = "urn:ietf:params:xml:ns:xmpp-streams";
+/// RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core
 pub const STREAM: &str = "http://etherx.jabber.org/streams";
 /// RFC 6120: Extensible Messaging and Presence Protocol (XMPP): Core
 pub const TLS: &str = "urn:ietf:params:xml:ns:xmpp-tls";
diff --git a/parsers/src/stream_error.rs b/parsers/src/stream_error.rs
index 317f131d7bfe9a260e718fa4c874fa90858c034d..1d6b64b76bc0113c47ee4779c188d9ac039451c0 100644
--- a/parsers/src/stream_error.rs
+++ b/parsers/src/stream_error.rs
@@ -17,7 +17,7 @@ use crate::ns;
 ///
 ///    [RFC 6120]: https://datatracker.ietf.org/doc/html/rfc6120#section-4.9.3
 #[derive(FromXml, AsXml, PartialEq, Debug, Clone)]
-#[xml(namespace = ns::STREAM)]
+#[xml(namespace = ns::XMPP_STREAMS)]
 pub enum DefinedCondition {
     /// The entity has sent XML that cannot be processed.
     ///
@@ -360,3 +360,22 @@ impl fmt::Display for SentStreamError {
 }
 
 impl Error for SentStreamError {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_condition_from_prosody() {
+        let doc = "<undefined-condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'/>";
+        let err: DefinedCondition = xso::from_bytes(doc.as_bytes()).unwrap();
+        assert_eq!(err, DefinedCondition::UndefinedCondition);
+    }
+
+    #[test]
+    fn parses_stream_error_from_prosody() {
+        let doc = "<stream:error xmlns:stream='http://etherx.jabber.org/streams'><undefined-condition xmlns='urn:ietf:params:xml:ns:xmpp-streams'/><text xmlns='urn:ietf:params:xml:ns:xmpp-streams'>No stream features to proceed with</text></stream:error>";
+        let err: StreamError = xso::from_bytes(doc.as_bytes()).unwrap();
+        assert_eq!(err.condition, DefinedCondition::UndefinedCondition);
+    }
+}