diff --git a/egs/librispeech/ASR/zipformer/optim.py b/egs/librispeech/ASR/zipformer/optim.py
index 714d8db9a..aaffbfed5 100644
--- a/egs/librispeech/ASR/zipformer/optim.py
+++ b/egs/librispeech/ASR/zipformer/optim.py
@@ -298,11 +298,14 @@ class ScaledAdam(BatchedOptimizer):
             # case 2 or case 4
             # the input is groups of parameter or named parameter.
             for cur_group in iterable_or_groups:
-                assert "named_params" in cur_group
-                name_list = [x[0] for x in cur_group["named_params"]]
-                p_list = [x[1] for x in cur_group["named_params"]]
-                del cur_group["named_params"]
-                cur_group["params"] = p_list
+                if "named_params" in cur_group:
+                    name_list = [x[0] for x in cur_group["named_params"]]
+                    p_list = [x[1] for x in cur_group["named_params"]]
+                    del cur_group["named_params"]
+                    cur_group["params"] = p_list
+                else:
+                    assert "params" in cur_group
+                    name_list = ["foo" for _ in cur_group["params"]]
                 param_groups.append(cur_group)
                 param_groups_names.append(name_list)