diff --git a/dockerjudge/__init__.py b/dockerjudge/__init__.py
index c7dae5d..9dbe119 100644
--- a/dockerjudge/__init__.py
+++ b/dockerjudge/__init__.py
@@ -118,22 +118,29 @@ def judge_test_cases(container, processor, tests, config):
     'Judge test cases'
     with ThreadPoolExecutor(max_workers=config.get('threads')) as executor:
         futures = []
-        for i, test in zip(range(1, len(tests) + 1), tests):
+        for i, test in zip(range(len(tests)), tests):
             futures.append(
                 executor.submit(test_case.__init__,
-                                container, processor, i, test, config)
+                                container, processor, i + 1, test, config)
             )
-            futures[-1].add_done_callback(done_callback)
-    return [future.result()[2] for future in futures]
-
-
-def done_callback(future):
-    'Callback'
-    result = future.result()
-    try:
-        result[0]['callback'].get('judge')(result[1], *result[2])
-    except TypeError:
-        pass
+            futures[-1].add_done_callback(done_callback(i, config))
+    return [
+        future.result()
+        if not future.exception() else (Status.UE, (None, None), .0)
+        for future in futures
+    ]
+
+
+def done_callback(i, config):
+    'Return the callback func for concurrent.futures.Future.add_done_callback'
+    def _done_callback(future):
+        result = ((Status.UE, (None, None), .0)
+                  if future.exception() else future.result())
+        try:
+            config['callback'].get('judge')(i, *result)
+        except TypeError:
+            pass
+    return _done_callback
 
 
 def run(container, processor, source, tests, config=None):
diff --git a/dockerjudge/test_case.py b/dockerjudge/test_case.py
index a15c8b5..1c3d6dd 100644
--- a/dockerjudge/test_case.py
+++ b/dockerjudge/test_case.py
@@ -12,14 +12,11 @@
 
 def __init__(container, processor, i, ioput, config):
     'Copy binary files to `i` and judge'
-    try:
-        container.exec_run(f'cp -r 0 {i}', workdir=str(processor.workdir))
-        exec_run(container, processor.before_judge, f'{processor.workdir}/{i}')
-        res = judge(container, processor, i, ioput, config)
-        exec_run(container, processor.after_judge, f'{processor.workdir}/{i}')
-        return config, i - 1, res
-    except Exception:  # pylint: disable = broad-except
-        return config, i - 1, [Status.UE, (None, None), .0]
+    container.exec_run(f'cp -r 0 {i}', workdir=str(processor.workdir))
+    exec_run(container, processor.before_judge, f'{processor.workdir}/{i}')
+    res = judge(container, processor, i, ioput, config)
+    exec_run(container, processor.after_judge, f'{processor.workdir}/{i}')
+    return res
 
 
 def _get_io_file_path(ioro, processor, i, config):