diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
index 81a9e36af..0291df4b0 100644
--- a/src/PIL/PngImagePlugin.py
+++ b/src/PIL/PngImagePlugin.py
@@ -636,6 +636,7 @@ class PngImageFile(ImageFile.ImageFile):
         if self.fp.read(8) != _MAGIC:
             raise SyntaxError("not a PNG file")
         self.__fp = self.fp
+        self.__frame = 0
 
         #
         # Parse headers up to the first IDAT or fDAT chunk

AttributeError: 'PngImageFile' object has no attribute '_PngImageFile__frame'
### What did you do?
My library BentoML is using imageio and Pillow in its tests, and with the latest release of Pillow 7.1.0 half an hour ago, I noticed some existing tests are breaking.

https://github.com/bentoml/BentoML
https://travis-ci.org/github/bentoml/BentoML/jobs/669765333?utm_medium=notification&utm_source=github_status

### What did you expect to happen?
`imageio.imread('./image.png')` should work

### What actually happened?

```
AttributeError: 'PngImageFile' object has no attribute '_PngImageFile__frame'
```
<img width="1043" alt="Screen Shot 2020-04-01 at 9 26 25 AM" src="https://user-images.githubusercontent.com/489344/78161998-18e70400-73fb-11ea-93f4-e210cd4f2636.png">

### What are your OS, Python and Pillow versions?

* OS:  mac os
* Python: 3.75
* Pillow: 7.1.0
* imageio: 2.8.0


```python
from imageio import imread
imread('./test.png')
```
It seems related to https://github.com/python-pillow/Pillow/pull/4243
diff --git a/Tests/test_file_png.py b/Tests/test_file_png.py
index b6da36530..f4b0de81b 100644
--- a/Tests/test_file_png.py
+++ b/Tests/test_file_png.py
@@ -629,6 +629,14 @@ class TestFilePng:
         with Image.open(test_file) as reloaded:
             assert reloaded.info["exif"] == b"Exif\x00\x00exifstring"
 
+    def test_tell(self, tmp_path):
+        with Image.open(TEST_PNG_FILE) as im:
+            assert im.tell() == 0
+
+    def test_seek(self, tmp_path):
+        with Image.open(TEST_PNG_FILE) as im:
+            im.seek(0)
+
 
 @pytest.mark.skipif(is_win32(), reason="Requires Unix or macOS")
 @skip_unless_feature("zlib")

pip install -e .[dev]
parse_log_pytest
requirements.txt
apt-get update apt-get install -y gcc libjpeg-dev zlib1g-dev libtiff5-dev libfreetype6-dev liblcms2-dev libwebp-dev tcl8.6-dev tk8.6-dev libharfbuzz-dev libfribidi-dev libxcb1-dev
3.9
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
alabaster==0.7.16
babel==2.17.0
black==25.1.0
blessed==1.20.0
build==1.2.2.post1
certifi==2025.1.31
charset-normalizer==3.4.1
check-manifest==0.50
click==8.1.8
coverage==7.8.0
docutils==0.21.2
exceptiongroup==1.2.2
idna==3.10
imagesize==1.4.1
importlib_metadata==8.6.1
iniconfig==2.1.0
jarn.viewdoc==2.7
Jinja2==3.1.6
MarkupSafe==3.0.2
mypy-extensions==1.0.0
olefile==0.47
packaging==24.2
pathspec==0.12.1
-e git+https://github.com/python-pillow/Pillow.git@0a77f73ef3b4d4086dae0cdd291ddb854d626538#egg=Pillow
platformdirs==4.3.7
pluggy==1.5.0
pycodestyle==2.13.0
pyflakes==3.3.1
Pygments==2.19.1
pyproject_hooks==1.2.0
pyroma==4.2
pytest==8.3.5
pytest-cov==6.0.0
requests==2.32.3
six==1.17.0
snowballstemmer==2.2.0
Sphinx==7.4.7
sphinx-rtd-theme==3.0.2
sphinxcontrib-applehelp==2.0.0
sphinxcontrib-devhelp==2.0.0
sphinxcontrib-htmlhelp==2.1.0
sphinxcontrib-jquery==4.1
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==2.0.0
sphinxcontrib-serializinghtml==2.0.0
tomli==2.2.1
trove-classifiers==2025.3.19.19
typing_extensions==4.13.0
urllib3==2.3.0
wcwidth==0.2.13
zipp==3.21.0

name: Pillow
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=3.0.16=h5eee18b_0
  - pip=25.0=py39h06a4308_0
  - python=3.9.21=he870216_1
  - readline=8.2=h5eee18b_0
  - setuptools=75.8.0=py39h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tzdata=2025a=h04d1e81_0
  - wheel=0.45.1=py39h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - alabaster==0.7.16
      - babel==2.17.0
      - black==25.1.0
      - blessed==1.20.0
      - build==1.2.2.post1
      - certifi==2025.1.31
      - charset-normalizer==3.4.1
      - check-manifest==0.50
      - click==8.1.8
      - coverage==7.8.0
      - docutils==0.21.2
      - exceptiongroup==1.2.2
      - idna==3.10
      - imagesize==1.4.1
      - importlib-metadata==8.6.1
      - iniconfig==2.1.0
      - jarn-viewdoc==2.7
      - jinja2==3.1.6
      - markupsafe==3.0.2
      - mypy-extensions==1.0.0
      - olefile==0.47
      - packaging==24.2
      - pathspec==0.12.1
      - platformdirs==4.3.7
      - pluggy==1.5.0
      - pycodestyle==2.13.0
      - pyflakes==3.3.1
      - pygments==2.19.1
      - pyproject-hooks==1.2.0
      - pyroma==4.2
      - pytest==8.3.5
      - pytest-cov==6.0.0
      - requests==2.32.3
      - six==1.17.0
      - snowballstemmer==2.2.0
      - sphinx==7.4.7
      - sphinx-rtd-theme==3.0.2
      - sphinxcontrib-applehelp==2.0.0
      - sphinxcontrib-devhelp==2.0.0
      - sphinxcontrib-htmlhelp==2.1.0
      - sphinxcontrib-jquery==4.1
      - sphinxcontrib-jsmath==1.0.1
      - sphinxcontrib-qthelp==2.0.0
      - sphinxcontrib-serializinghtml==2.0.0
      - tomli==2.2.1
      - trove-classifiers==2025.3.19.19
      - typing-extensions==4.13.0
      - urllib3==2.3.0
      - wcwidth==0.2.13
      - zipp==3.21.0
prefix: /opt/conda/envs/Pillow

Tests/test_file_png.py::TestFilePng::test_tell Tests/test_file_png.py::TestFilePng::test_seek
Tests/test_file_png.py::TestFilePng::test_load_verify
Tests/test_file_png.py::TestFilePng::test_sanity Tests/test_file_png.py::TestFilePng::test_invalid_file Tests/test_file_png.py::TestFilePng::test_broken Tests/test_file_png.py::TestFilePng::test_bad_text Tests/test_file_png.py::TestFilePng::test_bad_ztxt Tests/test_file_png.py::TestFilePng::test_bad_itxt Tests/test_file_png.py::TestFilePng::test_interlace Tests/test_file_png.py::TestFilePng::test_load_transparent_p Tests/test_file_png.py::TestFilePng::test_load_transparent_rgb Tests/test_file_png.py::TestFilePng::test_save_p_transparent_palette Tests/test_file_png.py::TestFilePng::test_save_p_single_transparency Tests/test_file_png.py::TestFilePng::test_save_p_transparent_black Tests/test_file_png.py::TestFilePng::test_save_greyscale_transparency Tests/test_file_png.py::TestFilePng::test_save_rgb_single_transparency Tests/test_file_png.py::TestFilePng::test_verify_struct_error Tests/test_file_png.py::TestFilePng::test_verify_ignores_crc_error Tests/test_file_png.py::TestFilePng::test_verify_not_ignores_crc_error_in_required_chunk Tests/test_file_png.py::TestFilePng::test_roundtrip_dpi Tests/test_file_png.py::TestFilePng::test_load_dpi_rounding Tests/test_file_png.py::TestFilePng::test_save_dpi_rounding Tests/test_file_png.py::TestFilePng::test_roundtrip_text Tests/test_file_png.py::TestFilePng::test_roundtrip_itxt Tests/test_file_png.py::TestFilePng::test_nonunicode_text Tests/test_file_png.py::TestFilePng::test_unicode_text Tests/test_file_png.py::TestFilePng::test_scary Tests/test_file_png.py::TestFilePng::test_trns_rgb Tests/test_file_png.py::TestFilePng::test_trns_p Tests/test_file_png.py::TestFilePng::test_trns_null Tests/test_file_png.py::TestFilePng::test_save_icc_profile Tests/test_file_png.py::TestFilePng::test_discard_icc_profile Tests/test_file_png.py::TestFilePng::test_roundtrip_icc_profile Tests/test_file_png.py::TestFilePng::test_roundtrip_no_icc_profile Tests/test_file_png.py::TestFilePng::test_repr_png Tests/test_file_png.py::TestFilePng::test_chunk_order Tests/test_file_png.py::TestFilePng::test_getchunks Tests/test_file_png.py::TestFilePng::test_textual_chunks_after_idat Tests/test_file_png.py::TestFilePng::test_exif[Tests/images/exif.png] Tests/test_file_png.py::TestFilePng::test_exif[Tests/images/exif_imagemagick.png] Tests/test_file_png.py::TestFilePng::test_exif_save Tests/test_file_png.py::TestFilePng::test_exif_from_jpg Tests/test_file_png.py::TestFilePng::test_exif_argument Tests/test_file_png.py::TestTruncatedPngPLeaks::test_leak_load
src/PIL/PngImagePlugin.py
src/PIL/PngImagePlugin.py