diff --git a/av/container/core.pyi b/av/container/core.pyi
index c33f3a4dc..862f0d326 100644
--- a/av/container/core.pyi
+++ b/av/container/core.pyi
@@ -4,6 +4,7 @@ from types import TracebackType
 from typing import Any, Callable, Literal, Type, overload
 
 from av.enum import EnumFlag
+from av.format import ContainerFormat
 
 from .input import InputContainer
 from .output import OutputContainer
@@ -36,7 +37,7 @@ class Container:
     input_was_opened: bool
     io_open: Any
     open_files: Any
-    format: str | None
+    format: ContainerFormat
     options: dict[str, str]
     container_options: dict[str, str]
     stream_options: list[str]
diff --git a/av/container/output.pyi b/av/container/output.pyi
index 0400dadbb..6df32c897 100644
--- a/av/container/output.pyi
+++ b/av/container/output.pyi
@@ -17,5 +17,5 @@ class OutputContainer(Container):
     ) -> Stream: ...
     def start_encoding(self) -> None: ...
     def close(self) -> None: ...
-    def mux(self, packets: Sequence[Packet]) -> None: ...
+    def mux(self, packets: Packet | Sequence[Packet]) -> None: ...
     def mux_one(self, packet: Packet) -> None: ...
diff --git a/av/format.pyi b/av/format.pyi
index 874920928..d2aef4764 100644
--- a/av/format.pyi
+++ b/av/format.pyi
@@ -22,9 +22,10 @@ class Flags(EnumFlag):
     SEEK_TO_PTS: int
 
 class ContainerFormat:
+    name: str
+    long_name: str
     is_input: bool
     is_output: bool
-    long_name: str
 
     # flags
     no_file: int
diff --git a/av/video/plane.pyi b/av/video/plane.pyi
index 9bc1f0d77..e4a0a206c 100644
--- a/av/video/plane.pyi
+++ b/av/video/plane.pyi
@@ -1,6 +1,8 @@
+from av.plane import Plane
+
 from .frame import VideoFrame
 
-class VideoPlane:
+class VideoPlane(Plane):
     line_size: int
     width: int
     height: int
diff --git a/av/video/stream.pyi b/av/video/stream.pyi
index 7ff1a4034..4b78efd06 100644
--- a/av/video/stream.pyi
+++ b/av/video/stream.pyi
@@ -1,5 +1,5 @@
 from fractions import Fraction
-from typing import Any, Literal
+from typing import Any, Iterator, Literal
 
 from av.packet import Packet
 from av.stream import Stream
@@ -36,4 +36,5 @@ class VideoStream(Stream):
     type: Literal["video"]
 
     def encode(self, frame: VideoFrame | None = None) -> list[Packet]: ...
+    def encode_lazy(self, frame: VideoFrame | None = None) -> Iterator[Packet]: ...
     def decode(self, packet: Packet | None = None) -> list[VideoFrame]: ...
diff --git a/tests/common.py b/tests/common.py
index e2b5f4e16..6c2b2d2e1 100644
--- a/tests/common.py
+++ b/tests/common.py
@@ -8,17 +8,18 @@
 from av.datasets import fate as fate_suite
 
 try:
-    import PIL.Image as Image
-    import PIL.ImageFilter as ImageFilter
+    import PIL  # noqa
+
+    has_pillow = True
 except ImportError:
-    Image = ImageFilter = None
+    has_pillow = False
 
 
 is_windows = os.name == "nt"
 skip_tests = frozenset(os.environ.get("PYAV_SKIP_TESTS", "").split(","))
 
 
-def makedirs(path):
+def makedirs(path: str) -> None:
     try:
         os.makedirs(path)
     except OSError as e:
@@ -29,23 +30,21 @@ def makedirs(path):
 _start_time = datetime.datetime.now()
 
 
-def _sandbox(timed=False):
+def _sandbox(timed: bool = False) -> str:
     root = os.path.abspath(os.path.join(__file__, "..", "..", "sandbox"))
 
-    sandbox = (
-        os.path.join(
-            root,
-            _start_time.strftime("%Y%m%d-%H%M%S"),
-        )
-        if timed
-        else root
-    )
+    if timed:
+        sandbox = os.path.join(root, _start_time.strftime("%Y%m%d-%H%M%S"))
+    else:
+        sandbox = root
+
     if not os.path.exists(sandbox):
         os.makedirs(sandbox)
+
     return sandbox
 
 
-def asset(*args):
+def asset(*args: str) -> str:
     adir = os.path.dirname(__file__)
     return os.path.abspath(os.path.join(adir, "assets", *args))
 
@@ -148,6 +147,8 @@ def assertNdarraysEqual(self, a, b):
             self.fail("ndarrays contents differ\n%s" % msg)
 
     def assertImagesAlmostEqual(self, a, b, epsilon=0.1, *args):
+        import PIL.ImageFilter as ImageFilter
+
         self.assertEqual(a.size, b.size, "sizes dont match")
         a = a.filter(ImageFilter.BLUR).getdata()
         b = b.filter(ImageFilter.BLUR).getdata()
diff --git a/tests/test_colorspace.py b/tests/test_colorspace.py
index 99c9f2fa2..571e7bd2b 100644
--- a/tests/test_colorspace.py
+++ b/tests/test_colorspace.py
@@ -5,7 +5,7 @@
 
 
 class TestColorSpace(TestCase):
-    def test_penguin_joke(self):
+    def test_penguin_joke(self) -> None:
         container = av.open(
             fate_suite("amv/MTV_high_res_320x240_sample_Penguin_Joke_MTV_from_WMV.amv")
         )
@@ -26,7 +26,7 @@ def test_penguin_joke(self):
                 self.assertEqual(frame.colorspace, Colorspace.ITU601)
                 return
 
-    def test_sky_timelapse(self):
+    def test_sky_timelapse(self) -> None:
         container = av.open(
             av.datasets.curated("pexels/time-lapse-video-of-night-sky-857195.mp4")
         )
diff --git a/tests/test_encode.py b/tests/test_encode.py
index d0939470a..e4336c735 100644
--- a/tests/test_encode.py
+++ b/tests/test_encode.py
@@ -1,6 +1,7 @@
 import io
 import math
 from fractions import Fraction
+from typing import cast
 from unittest import SkipTest
 
 import numpy as np
@@ -10,21 +11,23 @@
 from av.audio.stream import AudioStream
 from av.video.stream import VideoStream
 
-from .common import Image, TestCase, fate_suite
+from .common import TestCase, fate_suite, has_pillow
 
 WIDTH = 320
 HEIGHT = 240
 DURATION = 48
 
 
-def write_rgb_rotate(output):
-    if not Image:
-        raise SkipTest()
+def write_rgb_rotate(output: av.container.OutputContainer) -> None:
+    if not has_pillow:
+        raise SkipTest("Don't have Pillow")
+
+    import PIL.Image as Image
 
     output.metadata["title"] = "container"
     output.metadata["key"] = "value"
 
-    stream = output.add_stream("mpeg4", 24)
+    stream = cast(VideoStream, output.add_stream("mpeg4", 24))
     stream.width = WIDTH
     stream.height = HEIGHT
     stream.pix_fmt = "yuv420p"
diff --git a/tests/test_enums.py b/tests/test_enums.py
index 39bf856ad..8e4839a77 100644
--- a/tests/test_enums.py
+++ b/tests/test_enums.py
@@ -10,15 +10,7 @@
 
 class TestEnums(TestCase):
     def define_foobar(self, **kwargs):
-        return define_enum(
-            "Foobar",
-            __name__,
-            (
-                ("FOO", 1),
-                ("BAR", 2),
-            ),
-            **kwargs
-        )
+        return define_enum("Foobar", __name__, (("FOO", 1), ("BAR", 2)), **kwargs)
 
     def test_basics(self):
         cls = self.define_foobar()
diff --git a/tests/test_filters.py b/tests/test_filters.py
index dd090fe1d..326ef7fb9 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -1,6 +1,5 @@
 import errno
 from fractions import Fraction
-from unittest import SkipTest
 
 import numpy as np
 
@@ -9,7 +8,7 @@
 from av.audio.frame import format_dtypes
 from av.filter import Filter, Graph
 
-from .common import Image, TestCase, fate_suite
+from .common import TestCase, has_pillow
 
 
 def generate_audio_frame(
@@ -86,7 +85,7 @@ def test_generator_graph(self):
         frame = sink.pull()
         self.assertIsInstance(frame, VideoFrame)
 
-        if Image:
+        if has_pillow:
             frame.to_image().save(self.sandboxed("mandelbrot2.png"))
 
     def test_auto_find_sink(self):
@@ -97,7 +96,7 @@ def test_auto_find_sink(self):
 
         frame = graph.pull()
 
-        if Image:
+        if has_pillow:
             frame.to_image().save(self.sandboxed("mandelbrot3.png"))
 
     def test_delegate_sink(self):
@@ -108,43 +107,9 @@ def test_delegate_sink(self):
 
         frame = src.pull()
 
-        if Image:
+        if has_pillow:
             frame.to_image().save(self.sandboxed("mandelbrot4.png"))
 
-    def test_haldclut_graph(self):
-        raise SkipTest()
-
-        graph = Graph()
-
-        img = Image.open(fate_suite("png1/lena-rgb24.png"))
-        frame = VideoFrame.from_image(img)
-        img_source = graph.add_buffer(frame)
-
-        hald_img = Image.open("hald_7.png")
-        hald_frame = VideoFrame.from_image(hald_img)
-        hald_source = graph.add_buffer(hald_frame)
-
-        hald_filter = graph.add("haldclut")
-
-        sink = graph.add("buffersink")
-
-        img_source.link(0, hald_filter, 0)
-        hald_source.link(0, hald_filter, 1)
-        hald_filter.link(0, sink, 0)
-        graph.config()
-
-        self.assertIs(img_source.outputs[0].linked_to, hald_filter.inputs[0])
-        self.assertIs(hald_source.outputs[0].linked_to, hald_filter.inputs[1])
-        self.assertIs(hald_filter.outputs[0].linked_to, sink.inputs[0])
-
-        hald_source.push(hald_frame)
-
-        img_source.push(frame)
-
-        frame = sink.pull()
-        self.assertIsInstance(frame, VideoFrame)
-        frame.to_image().save(self.sandboxed("filtered.png"))
-
     def test_audio_buffer_sink(self):
         graph = Graph()
         audio_buffer = graph.add_abuffer(
diff --git a/tests/test_python_io.py b/tests/test_python_io.py
index 84e94d7a3..42b8dd132 100644
--- a/tests/test_python_io.py
+++ b/tests/test_python_io.py
@@ -3,7 +3,14 @@
 
 import av
 
-from .common import Image, MethodLogger, TestCase, fate_png, fate_suite, run_in_sandbox
+from .common import (
+    MethodLogger,
+    TestCase,
+    fate_png,
+    fate_suite,
+    has_pillow,
+    run_in_sandbox,
+)
 from .test_encode import assert_rgb_rotate, write_rgb_rotate
 
 
@@ -206,9 +213,11 @@ def test_writing_to_custom_io_dash(self):
             assert_rgb_rotate(self, container, is_dash=True)
 
     def test_writing_to_custom_io_image2(self):
-        if not Image:
+        if not has_pillow:
             raise SkipTest()
 
+        import PIL.Image as Image
+
         # Custom I/O that opens file and logs calls
         wrapped_custom_io = CustomIOLogger()
 
@@ -263,7 +272,7 @@ def test_writing_to_custom_io_image2(self):
             self.assertEqual(stream.format.width, width)
             self.assertEqual(stream.format.height, height)
 
-    def test_writing_to_file(self):
+    def test_writing_to_file(self) -> None:
         path = self.sandboxed("writing.mp4")
 
         with open(path, "wb") as fh:
@@ -273,7 +282,7 @@ def test_writing_to_file(self):
         with av.open(path) as container:
             assert_rgb_rotate(self, container)
 
-    def test_writing_to_pipe_readonly(self):
+    def test_writing_to_pipe_readonly(self) -> None:
         buf = ReadOnlyPipe()
         with self.assertRaises(ValueError) as cm:
             self.write(buf)
@@ -291,10 +300,10 @@ def test_writing_to_pipe_writeonly(self):
             str(cm.exception),
         )
 
-    def read(self, fh, seekable=True):
+    def read(self, fh, seekable: bool = True) -> None:
         wrapped = MethodLogger(fh)
 
-        with av.open(wrapped) as container:
+        with av.open(wrapped, "r") as container:
             self.assertEqual(container.format.name, "mpegts")
             self.assertEqual(
                 container.format.long_name, "MPEG-TS (MPEG-2 Transport Stream)"
diff --git a/tests/test_videoframe.py b/tests/test_videoframe.py
index 32f6c6cd3..28540ccc3 100644
--- a/tests/test_videoframe.py
+++ b/tests/test_videoframe.py
@@ -4,7 +4,7 @@
 
 from av import VideoFrame
 
-from .common import Image, TestCase, fate_png
+from .common import TestCase, fate_png, has_pillow
 
 
 class TestVideoFrameConstructors(TestCase):
@@ -90,10 +90,12 @@ def test_memoryview_read(self):
 
 class TestVideoFrameImage(TestCase):
     def setUp(self):
-        if not Image:
+        if not has_pillow:
             raise SkipTest()
 
     def test_roundtrip(self):
+        import PIL.Image as Image
+
         image = Image.open(fate_png())
         frame = VideoFrame.from_image(image)
         img = frame.to_image()