diff --git a/pyproject.toml b/pyproject.toml
index b342bc001f6..18b251f1d75 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -65,7 +65,6 @@ dependencies = [
   "backports.cached-property;python_version<'3.8'",
   "backports.shutil_copytree;python_version<'3.8'",
   "importlib-metadata;python_version<'3.8'",
-  "singledispatchmethod;python_version<'3.8'",
 ]
 dynamic = ["version"]
 
diff --git a/src/bentoml/_internal/io_descriptors/image.py b/src/bentoml/_internal/io_descriptors/image.py
index 8a3b156b999..f7e540a20b7 100644
--- a/src/bentoml/_internal/io_descriptors/image.py
+++ b/src/bentoml/_internal/io_descriptors/image.py
@@ -231,8 +231,6 @@ def from_sample(
 
         if LazyType["ext.NpNDArray"]("numpy.ndarray").isinstance(sample):
             sample = PIL.Image.fromarray(sample, mode=pilmode)
-        elif LazyType["PIL.Image.Image"]("PIL.Image.Image").isinstance(sample):
-            sample = sample
         elif isinstance(sample, str):
             p = resolve_user_filepath(sample, ctx=None)
             try:
diff --git a/src/bentoml/_internal/io_descriptors/pandas.py b/src/bentoml/_internal/io_descriptors/pandas.py
index 91a58a4eb31..cacb1d1e90d 100644
--- a/src/bentoml/_internal/io_descriptors/pandas.py
+++ b/src/bentoml/_internal/io_descriptors/pandas.py
@@ -469,20 +469,12 @@ def _convert_dtype(
             return None
 
     def to_spec(self) -> dict[str, t.Any]:
-        # TODO: support extension dtypes
-        dtype = None
-        if self._dtype is not None:
-            if isinstance(self._dtype, bool):
-                dtype = self._dtype
-            else:
-                dtype = self._dtype.name
-
         return {
             "id": self.descriptor_id,
             "args": {
                 "orient": self._orient,
                 "columns": self._columns,
-                "dtype": self._convert_dtype(dtype),
+                "dtype": self._convert_dtype(self._dtype),
                 "shape": self._shape,
                 "enforce_dtype": self._enforce_dtype,
                 "enforce_shape": self._enforce_shape,
diff --git a/tests/unit/_internal/io/test_base.py b/tests/unit/_internal/io/test_base.py
index ddf91714006..ca2065290da 100644
--- a/tests/unit/_internal/io/test_base.py
+++ b/tests/unit/_internal/io/test_base.py
@@ -2,12 +2,15 @@
 
 import typing as t
 from typing import TYPE_CHECKING
-from bentoml.io import IODescriptor
+
 import pytest
 
+from bentoml.io import IODescriptor
+
 if TYPE_CHECKING:
 
     from typing_extensions import Self
+
     from bentoml._internal.context import InferenceApiContext as Context