diff --git a/joj3_config_generator/models/result.py b/joj3_config_generator/models/result.py
index 4f964b8..308c73a 100644
--- a/joj3_config_generator/models/result.py
+++ b/joj3_config_generator/models/result.py
@@ -39,7 +39,7 @@ class StreamOut(BaseModel):
     stream_out: bool = Field(..., alias="streamOut")
 
 
-InputFile = Union[LocalFile, MemoryFile, PreparedFile, Symlink]
+InputFile = Union[LocalFile, MemoryFile, PreparedFile, Symlink, None]
 
 
 class Cmd(BaseModel):
diff --git a/joj3_config_generator/transformers/task.py b/joj3_config_generator/transformers/task.py
index e1b98ca..8f070cc 100644
--- a/joj3_config_generator/transformers/task.py
+++ b/joj3_config_generator/transformers/task.py
@@ -238,6 +238,7 @@ def fix_diff(
         )
         parser_cases.append(parser_case)
     executor.with_.cases = stage_cases
+    executor.with_.default.stdin = None
     diff_parser.with_ = result.DiffConfig(name="diff", cases=parser_cases)
 
 
diff --git a/tests/convert/basic/task.json b/tests/convert/basic/task.json
index 82e35e4..6fa7a38 100644
--- a/tests/convert/basic/task.json
+++ b/tests/convert/basic/task.json
@@ -432,9 +432,6 @@
                             "env": [
                                 "PATH=/usr/bin:/bin:/usr/local/bin"
                             ],
-                            "stdin": {
-                                "content": ""
-                            },
                             "stdout": {
                                 "name": "stdout",
                                 "max": 33554432,
@@ -678,9 +675,6 @@
                             "env": [
                                 "PATH=/usr/bin:/bin:/usr/local/bin"
                             ],
-                            "stdin": {
-                                "content": ""
-                            },
                             "stdout": {
                                 "name": "stdout",
                                 "max": 33554432,
diff --git a/tests/convert/diff/task.json b/tests/convert/diff/task.json
index 63a4607..91ec29c 100644
--- a/tests/convert/diff/task.json
+++ b/tests/convert/diff/task.json
@@ -24,9 +24,6 @@
                             "env": [
                                 "PATH=/usr/bin:/bin:/usr/local/bin"
                             ],
-                            "stdin": {
-                                "content": ""
-                            },
                             "stdout": {
                                 "name": "stdout",
                                 "max": 33554432,