diff --git a/source/org/jivesoftware/smackx/ServiceDiscoveryManager.java b/source/org/jivesoftware/smackx/ServiceDiscoveryManager.java
index 2b4f23f5b..a42e5e1bf 100644
--- a/source/org/jivesoftware/smackx/ServiceDiscoveryManager.java
+++ b/source/org/jivesoftware/smackx/ServiceDiscoveryManager.java
@@ -190,7 +190,7 @@ public class ServiceDiscoveryManager {
         Set<Identity> res = new HashSet<Identity>(identities);
         // Add the default identity that must exist
         res.add(defaultIdentity);
-        return res;
+        return Collections.unmodifiableSet(res);
     }
 
     /**