diff --git a/pySim/tlv.py b/pySim/tlv.py
index 22a14cd..3e245b5 100644
--- a/pySim/tlv.py
+++ b/pySim/tlv.py
@@ -395,7 +395,7 @@
                     res.append(inst)
                 else:
                     raise ValueError('%s: Unknown TLV Class %s in %s; expected %s' %
-                                     (self, i[0], decoded, self.members_by_name.keys()))
+                                     (self, k, decoded, self.members_by_name.keys()))
         self.children = res
         return res