diff --git a/lib/ynl.py b/lib/ynl.py
index 363f029..44a5af4 100644
--- a/lib/ynl.py
+++ b/lib/ynl.py
@@ -753,7 +753,7 @@ def _decode_sub_msg(self, attr, attr_spec, search_attrs):
                 decoded.update(subdict)
             else:
                 raise Exception(
-                    f"Unknown attribute-set '{attr_space}' when decoding '{attr_spec.name}'"
+                    f"Unknown attribute-set '{msg_format.attr_set}' when decoding '{attr_spec.name}'"
                 )
         return decoded