diff --git a/torchpack/distributed/comm.py b/torchpack/distributed/comm.py
index e5cdc3d..43c523f 100644
--- a/torchpack/distributed/comm.py
+++ b/torchpack/distributed/comm.py
@@ -13,9 +13,11 @@ def allreduce(data: Any, reduction: str = 'sum') -> Any:
     data = allgather(data)
     if reduction == 'sum':
         return sum(data)
+    else:
+        raise NotImplementedError(reduction)
 
 
-def allgather(data: Any) -> List:
+def allgather(data: Any) -> List[Any]:
     world_size = context.size()
     if world_size == 1:
         return [data]
diff --git a/torchpack/launch/launchers/drunner.py b/torchpack/launch/launchers/drunner.py
index 8d6225c..bb80430 100644
--- a/torchpack/launch/launchers/drunner.py
+++ b/torchpack/launch/launchers/drunner.py
@@ -9,7 +9,7 @@
 __all__ = ['main']
 
 
-def is_exportable(v):
+def is_exportable(v) -> bool:
     IGNORE_REGEXES = ['BASH_FUNC_.*', 'OLDPWD']
     return not any(re.match(r, v) for r in IGNORE_REGEXES)
 
diff --git a/torchpack/train/trainer.py b/torchpack/train/trainer.py
index d5a77c6..5fe2360 100644
--- a/torchpack/train/trainer.py
+++ b/torchpack/train/trainer.py
@@ -6,11 +6,12 @@
 from torchpack.callbacks import (Callback, Callbacks, ConsoleWriter,
                                  EstimatedTimeLeft, JSONLWriter, MetaInfoSaver,
                                  ProgressBar, TFEventWriter)
-from torchpack.train.exception import StopTraining
-from torchpack.train.summary import Summary
 from torchpack.utils import humanize
 from torchpack.utils.logging import logger
 
+from .exception import StopTraining
+from .summary import Summary
+
 __all__ = ['Trainer']
 
 
@@ -35,10 +36,12 @@ def train_with_defaults(
             ProgressBar(),
             EstimatedTimeLeft()
         ]
-        self.train(dataflow=dataflow,
-                   num_epochs=num_epochs,
-                   steps_per_epoch=steps_per_epoch,
-                   callbacks=callbacks)
+        self.train(
+            dataflow=dataflow,
+            num_epochs=num_epochs,
+            steps_per_epoch=steps_per_epoch,
+            callbacks=callbacks,
+        )
 
     def train(
         self,
diff --git a/torchpack/utils/config.py b/torchpack/utils/config.py
index 799ea0d..f06d410 100644
--- a/torchpack/utils/config.py
+++ b/torchpack/utils/config.py
@@ -6,7 +6,7 @@
 
 from multimethod import multimethod
 
-from . import io
+from torchpack.utils import io
 
 __all__ = ['Config', 'configs']
 
diff --git a/torchpack/utils/matching.py b/torchpack/utils/matching.py
index f06fc41..4474611 100644
--- a/torchpack/utils/matching.py
+++ b/torchpack/utils/matching.py
@@ -6,7 +6,7 @@
 
 class NameMatcher:
 
-    def __init__(self, patterns: Optional[Union[str, List[str]]]):
+    def __init__(self, patterns: Optional[Union[str, List[str]]]) -> None:
         if patterns is None:
             patterns = []
         elif isinstance(patterns, str):