diff --git a/src/dflow/dag.py b/src/dflow/dag.py
index 6d053de7..ae31dda4 100644
--- a/src/dflow/dag.py
+++ b/src/dflow/dag.py
@@ -9,7 +9,7 @@
                      task_output_parameter_pattern)
 from .config import config, s3_config
 from .context_syntax import GLOBAL_CONTEXT
-from .io import Inputs, Outputs
+from .io import Inputs, Outputs, OutputArtifact
 from .op_template import OPTemplate
 from .step import add_slices
 from .task import Task
@@ -281,6 +281,9 @@ def run(self, workflow_id=None, context=None, stepdir=None):
                     self.tasks[j].outputs.parameters[
                         name].value = value
                 for name, path in arts.items():
+                    if name not in self.tasks[j].outputs.artifacts:
+                        self.tasks[j].outputs.artifacts[name] = \
+                            OutputArtifact()
                     self.tasks[j].outputs.artifacts[
                         name].local_path = path
                 self.tasks[j].phase = phase