diff --git a/src/net/java/sip/communicator/impl/protocol/jabber/extensions/colibri/ColibriConferenceIQ.java b/src/net/java/sip/communicator/impl/protocol/jabber/extensions/colibri/ColibriConferenceIQ.java
index b86df2a58..563c15b62 100644
--- a/src/net/java/sip/communicator/impl/protocol/jabber/extensions/colibri/ColibriConferenceIQ.java
+++ b/src/net/java/sip/communicator/impl/protocol/jabber/extensions/colibri/ColibriConferenceIQ.java
@@ -339,6 +339,11 @@ public boolean addPayloadType(PayloadTypePacketExtension payloadType)
             if (payloadType == null)
                 throw new NullPointerException("payloadType");
 
+            // Make sure that the COLIBRI namespace is used.
+            payloadType.setNamespace(null);
+            for (ParameterPacketExtension p : payloadType.getParameters())
+                p.setNamespace(null);
+
             return
                 payloadTypes.contains(payloadType)
                     ? false