diff --git a/src/SOAPpy/SOAPBuilder.py b/src/SOAPpy/SOAPBuilder.py
index 2f8f392..f4f43fd 100644
--- a/src/SOAPpy/SOAPBuilder.py
+++ b/src/SOAPpy/SOAPBuilder.py
@@ -679,8 +679,10 @@ class SOAPBuilder:
             self.out.append('<%s%s%s>\n' % (tag, id, r))
 
             d1 = getattr(obj, '__dict__', None)
+            if d1 is None and hasattr(obj, "__slots__")
+                d1 = dict(((k, getattr(obj, k)) for k in obj.__slots__))
             if d1 is not None:
-                for (k, v) in d1:
+                for (k, v) in d1.items():
                     if k[0] != "_":
                         self.dump(v, k, 1, ns_map)