diff --git a/joj3_config_generator/processers/task.py b/joj3_config_generator/processers/task.py
index e21b208..52bcc74 100644
--- a/joj3_config_generator/processers/task.py
+++ b/joj3_config_generator/processers/task.py
@@ -152,55 +152,42 @@ def fix_file(file_parser_config: task.ParserFile, file_parser: result.Parser) ->
 def fix_diff(
     task_stage: task.Stage,
     diff_parser_config: result.Parser,
-    diff_executor: result.Executor,
+    diff_executor_config: result.Executor,
     base_dir: Path,
 ) -> None:
-    skip = task_stage.skip
-    cases = task_stage.cases
-    finalized_cases = [case for case in cases if case not in skip]
-
+    valid_cases = (
+        (case, task_stage.cases[case])
+        for case in task_stage.cases
+        if case not in task_stage.skip and case in task_stage.cases
+    )
     stage_cases = []
     parser_cases = []
-
-    for case in finalized_cases:
-        case_stage = task_stage.cases.get(case) if task_stage.cases else None
-        if not case_stage:
-            continue
-
-        cpu_limit = case_stage.limit.cpu
-        clock_limit = 2 * case_stage.limit.cpu
-        memory_limit = case_stage.limit.mem
-        command = case_stage.command
-        stdin = case_stage.in_ if case_stage.in_ != "" else f"{case}.in"
-        stdout = case_stage.out_ if case_stage.out_ != "" else f"{case}.out"
-
+    for case, case_stage in valid_cases:
         stage_cases.append(
             result.OptionalCmd(
                 stdin=result.LocalFile(
-                    src=str(base_dir / stdin),
+                    src=str(base_dir / (case_stage.in_ or f"{case}.in"))
                 ),
-                args=shlex.split(command) if command else None,
-                cpu_limit=cpu_limit,
-                clock_limit=clock_limit,
-                memory_limit=memory_limit,
+                args=shlex.split(case_stage.command) if case_stage.command else None,
+                cpu_limit=case_stage.limit.cpu,
+                clock_limit=2 * case_stage.limit.cpu,
+                memory_limit=case_stage.limit.mem,
                 proc_limit=50,
             )
         )
-        diff_output = case_stage.diff.output
         parser_cases.append(
             result.DiffCasesConfig(
                 outputs=[
                     result.DiffOutputConfig(
-                        score=diff_output.score,
+                        score=case_stage.diff.output.score,
                         file_name="stdout",
-                        answer_path=str(base_dir / stdout),
-                        force_quit_on_diff=diff_output.force_quit,
-                        always_hide=diff_output.hide,
-                        compare_space=not diff_output.ignore_spaces,
+                        answer_path=str(base_dir / (case_stage.out_ or f"{case}.out")),
+                        force_quit_on_diff=case_stage.diff.output.force_quit,
+                        always_hide=case_stage.diff.output.hide,
+                        compare_space=not case_stage.diff.output.ignore_spaces,
                     )
                 ]
             )
         )
-
-    diff_executor.with_.cases = stage_cases
+    diff_executor_config.with_.cases = stage_cases
     diff_parser_config.with_ = result.DiffConfig(name="diff", cases=parser_cases)