diff --git a/iwf/object_encoder.py b/iwf/object_encoder.py
index 19d3e7b..751bac9 100644
--- a/iwf/object_encoder.py
+++ b/iwf/object_encoder.py
@@ -228,8 +228,8 @@ def __init__(self) -> None:
         super().__init__(*DefaultPayloadConverter.default_encoding_payload_converters)
 
 
-class BinaryNullPayloadConverter(EncodingPayloadConverter):
-    """Converter for 'binary/null' payloads supporting None values."""
+class UnsetPayloadConverter(EncodingPayloadConverter):
+    """Converter for 'unset' payloads supporting None values."""
 
     @property
     def encoding(self) -> Union[str, Unset]:
@@ -253,6 +253,15 @@ def from_payload(
         return None
 
 
+class BinaryNullPayloadConverter(UnsetPayloadConverter):
+    """Converter for 'binary/null' payloads supporting None values."""
+
+    @property
+    def encoding(self) -> Union[str, Unset]:
+        """See base class."""
+        return "binary/null"
+
+
 class BinaryPlainPayloadConverter(EncodingPayloadConverter):
     """Converter for 'binary/plain' payloads supporting bytes values."""
 
@@ -533,6 +542,7 @@ def decode(
 
 
 DefaultPayloadConverter.default_encoding_payload_converters = (
+    UnsetPayloadConverter(),
     BinaryNullPayloadConverter(),
     BinaryPlainPayloadConverter(),
     JSONPlainPayloadConverter(),
diff --git a/iwf/tests/__init__.py b/iwf/tests/__init__.py
index c5f239d..0b733af 100644
--- a/iwf/tests/__init__.py
+++ b/iwf/tests/__init__.py
@@ -1,17 +1,18 @@
 from iwf.registry import Registry
-from iwf.tests.workflows.java_duplicate_rpc_memo_workflow import (
-    JavaDuplicateRpcMemoWorkflow,
-)
 from iwf.tests.workflows.abnormal_exit_workflow import AbnormalExitWorkflow
 from iwf.tests.workflows.basic_workflow import BasicWorkflow
 from iwf.tests.workflows.conditional_complete_workflow import (
     ConditionalCompleteWorkflow,
 )
 from iwf.tests.workflows.describe_workflow import DescribeWorkflow
+from iwf.tests.workflows.empty_data_workflow import EmptyDataWorkflow
 from iwf.tests.workflows.internal_channel_workflow import InternalChannelWorkflow
 from iwf.tests.workflows.internal_channel_workflow_with_no_prefix_channel import (
     InternalChannelWorkflowWithNoPrefixChannel,
 )
+from iwf.tests.workflows.java_duplicate_rpc_memo_workflow import (
+    JavaDuplicateRpcMemoWorkflow,
+)
 from iwf.tests.workflows.persistence_data_attributes_workflow import (
     PersistenceDataAttributesWorkflow,
 )
@@ -45,6 +46,7 @@
 registry.add_workflow(BasicWorkflow())
 registry.add_workflow(ConditionalCompleteWorkflow())
 registry.add_workflow(DescribeWorkflow())
+registry.add_workflow(EmptyDataWorkflow())
 registry.add_workflow(InternalChannelWorkflow())
 registry.add_workflow(InternalChannelWorkflowWithNoPrefixChannel())
 registry.add_workflow(JavaDuplicateRpcMemoWorkflow())
@@ -54,8 +56,8 @@
 registry.add_workflow(RecoveryWorkflow())
 registry.add_workflow(RpcMemoWorkflow())
 registry.add_workflow(RPCWorkflow())
-registry.add_workflow(TimerWorkflow())
 registry.add_workflow(StateOptionsOverrideWorkflow())
+registry.add_workflow(TimerWorkflow())
 registry.add_workflow(WaitForStateWithStateExecutionIdWorkflow())
 registry.add_workflow(WaitForStateWithWaitForKeyWorkflow())
 registry.add_workflow(WaitInternalChannelWorkflow())
diff --git a/iwf/tests/test_empty_data_decodes_properly.py b/iwf/tests/test_empty_data_decodes_properly.py
new file mode 100644
index 0000000..4188169
--- /dev/null
+++ b/iwf/tests/test_empty_data_decodes_properly.py
@@ -0,0 +1,65 @@
+import inspect
+import time
+import unittest
+
+import httpx
+
+from iwf.client import Client
+from iwf.tests.worker_server import registry
+from iwf.worker_service import WorkerService
+
+
+class TestBinaryNullDecodesCorrectly(unittest.TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.client = Client(registry)
+
+    def test_binary_null_input_decodes_correctly(self):
+        wf_id = f"{inspect.currentframe().f_code.co_name}-{time.time_ns()}"
+
+        response = httpx.post(
+            f"http://0.0.0.0:8802/{WorkerService.api_path_workflow_state_execute}",
+            json={
+                "DataObjects": [
+                    {"key": "test-da", "value": {"encoding": "binary/null"}}
+                ],
+                "commandResults": {
+                    "interStateChannelResults": [],
+                    "stateStartApiSucceeded": True,
+                },
+                "context": {
+                    "attempt": 1,
+                    "firstAttemptTimestamp": 1747935829,
+                    "stateExecutionId": "State1-1",
+                    "workflowId": wf_id,
+                    "workflowRunId": "0196f734-d037-7432-bd63-e1136cd34dbd",
+                    "workflowStartedTimestamp": 1747904155,
+                },
+                "stateInput": {"encoding": "binary/null"},
+                "stateLocals": [],
+                "workflowStateId": "State1",
+                "workflowType": "EmptyDataWorkflow",
+            },
+        )
+        assert response.is_success
+        response_json = response.json()
+        self.assertEqual(
+            response_json,
+            {
+                "publishToInterStateChannel": [],
+                "recordEvents": [],
+                "stateDecision": {
+                    "nextStates": [
+                        {
+                            "stateId": "_SYS_GRACEFUL_COMPLETING_WORKFLOW",
+                            "stateInput": {
+                                "data": '"success"',
+                                "encoding": "json/plain",
+                            },
+                        }
+                    ]
+                },
+                "upsertDataObjects": [],
+                "upsertStateLocals": [],
+            },
+        )
diff --git a/iwf/tests/workflows/empty_data_workflow.py b/iwf/tests/workflows/empty_data_workflow.py
new file mode 100644
index 0000000..ea2367e
--- /dev/null
+++ b/iwf/tests/workflows/empty_data_workflow.py
@@ -0,0 +1,37 @@
+from iwf.command_results import CommandResults
+from iwf.communication import Communication
+from iwf.persistence import Persistence
+from iwf.persistence_schema import PersistenceField, PersistenceSchema
+from iwf.state_decision import StateDecision
+from iwf.state_schema import StateSchema
+from iwf.workflow import ObjectWorkflow
+from iwf.workflow_context import WorkflowContext
+from iwf.workflow_state import WorkflowState
+
+TEST_DA_KEY = "test-da"
+
+
+class State1(WorkflowState[None]):
+    def execute(
+        self,
+        ctx: WorkflowContext,
+        input: None,
+        command_results: CommandResults,
+        persistence: Persistence,
+        communication: Communication,
+    ) -> StateDecision:
+        assert input is None
+        test_da = persistence.get_data_attribute(TEST_DA_KEY)
+        assert test_da is None
+
+        return StateDecision.graceful_complete_workflow(output="success")
+
+
+class EmptyDataWorkflow(ObjectWorkflow):
+    def get_workflow_states(self) -> StateSchema:
+        return StateSchema.with_starting_state(State1())
+
+    def get_persistence_schema(self) -> PersistenceSchema:
+        return PersistenceSchema.create(
+            PersistenceField.data_attribute_def(TEST_DA_KEY, None),
+        )