diff --git a/dpgen2/op/caly_evo_step_merge.py b/dpgen2/op/caly_evo_step_merge.py
index 77d3a9d3..8abda6dd 100644
--- a/dpgen2/op/caly_evo_step_merge.py
+++ b/dpgen2/op/caly_evo_step_merge.py
@@ -62,7 +62,7 @@ def get_input_sign(cls):
                 "iter_num": int,
                 "cnt_num": Parameter(int, default=0),
                 "block_id": Parameter(str, default=""),
-                "task_name": str,
+                "task_name": BigParameter(str),
                 "expl_config": BigParameter(dict),
                 "models": Artifact(Path),
                 "input_file": Artifact(Path),
diff --git a/dpgen2/op/collect_run_caly.py b/dpgen2/op/collect_run_caly.py
index e4e33210..4b6148f6 100644
--- a/dpgen2/op/collect_run_caly.py
+++ b/dpgen2/op/collect_run_caly.py
@@ -77,7 +77,7 @@ def get_input_sign(cls):
     def get_output_sign(cls):
         return OPIOSign(
             {
-                "task_name": Parameter(str),  # calypso_task.idx
+                "task_name": BigParameter(str),  # calypso_task.idx
                 "finished": Parameter(str),  # True if cnt_num == maxstep
                 "poscar_dir": Artifact(Path),  # dir contains POSCAR* of next step
                 "input_file": Artifact(Path),  # input.dat
diff --git a/dpgen2/op/prep_caly_dp_optim.py b/dpgen2/op/prep_caly_dp_optim.py
index 0b3035f2..d2e4d8b0 100644
--- a/dpgen2/op/prep_caly_dp_optim.py
+++ b/dpgen2/op/prep_caly_dp_optim.py
@@ -53,7 +53,7 @@ class PrepCalyDPOptim(OP):
     def get_input_sign(cls):
         return OPIOSign(
             {
-                "task_name": Parameter(str),  # calypso_task.idx
+                "task_name": BigParameter(str),  # calypso_task.idx
                 "finished": Parameter(str),
                 "template_slice_config": Parameter(dict),
                 "poscar_dir": Artifact(