diff --git a/targetran/_np_functional.py b/targetran/_np_functional.py
index 43e9abb..8284eb0 100644
--- a/targetran/_np_functional.py
+++ b/targetran/_np_functional.py
@@ -3,7 +3,7 @@
 """
 from typing import Tuple
 
-import cv2  # type: ignore
+import cv2
 import numpy as np
 
 from targetran._typing import (
@@ -80,7 +80,7 @@ def _np_boolean_mask(x: NDAnyArray, mask: NDBoolArray) -> NDAnyArray:
     """
     mask: boolean array
     """
-    return x[mask]  # type: ignore
+    return x[mask]
 
 
 def _np_gather_image(image: NDFloatArray, indices: NDIntArray) -> NDFloatArray:
diff --git a/targetran/np/_np.py b/targetran/np/_np.py
index b2bf669..da79927 100644
--- a/targetran/np/_np.py
+++ b/targetran/np/_np.py
@@ -286,7 +286,7 @@ def _get_mats(
             )
         else:
             conditions = rand_fn() < probs
-            indices = np.arange(len(probs), dtype=np.int32)[conditions]
+            indices = np.arange(len(probs), dtype=np.int32)[conditions]  # type: ignore
 
         if len(indices) > 1:
             if self._keep_order:
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29