diff --git a/src/fromager/dependencies.py b/src/fromager/dependencies.py
index 18dcdbef..51aa174d 100644
--- a/src/fromager/dependencies.py
+++ b/src/fromager/dependencies.py
@@ -5,11 +5,11 @@
 import os
 import pathlib
 import tempfile
+import tomllib
 import typing
 import zipfile
 
 import pyproject_hooks
-import tomlkit
 from packaging.metadata import Metadata
 from packaging.requirements import Requirement
 from packaging.utils import NormalizedName, canonicalize_name
@@ -492,7 +492,9 @@ def get_pyproject_contents(sdist_root_dir: pathlib.Path) -> dict[str, typing.Any
     pyproject_toml_filename = sdist_root_dir / "pyproject.toml"
     if not os.path.exists(pyproject_toml_filename):
         return {}
-    return tomlkit.loads(pyproject_toml_filename.read_text())
+    # Read-only parse: use stdlib tomllib, not tomlkit. tomlkit rejects some
+    # spec-valid files (out-of-order tables), e.g. #1356.
+    return tomllib.loads(pyproject_toml_filename.read_text())
 
 
 # From pypa/build/src/build/__main__.py
diff --git a/tests/test_dependencies.py b/tests/test_dependencies.py
index 34a68ee8..f97850fd 100644
--- a/tests/test_dependencies.py
+++ b/tests/test_dependencies.py
@@ -129,6 +129,33 @@ def test_get_build_backend(
     assert expected_results == actual
 
 
+def test_get_pyproject_contents_out_of_order_tables(tmp_path: pathlib.Path) -> None:
+    # Regression test for #1356: a spec-valid pyproject.toml that re-opens a
+    # super-table (created via dotted keys) out of order. tomlkit rejects this,
+    # stdlib tomllib accepts it.
+    tmp_path.joinpath("pyproject.toml").write_text(
+        textwrap.dedent("""\
+            [build-system]
+            requires = ["setuptools", "wheel"]
+            build-backend = "setuptools.build_meta"
+
+            [tool.ruff]
+            lint.extend-select = ["UP"]
+            lint.ignore = ["E402"]
+
+            [[tool.mypy.overrides]]
+            module = ["pkg.mod"]
+
+            [tool.ruff.lint.per-file-ignores]
+            "__init__.py" = ["F401"]
+            """)
+    )
+
+    contents = dependencies.get_pyproject_contents(tmp_path)
+
+    assert contents["build-system"]["requires"] == ["setuptools", "wheel"]
+
+
 def _clean_build_artifacts(f: typing.Callable[..., None]) -> typing.Callable[..., None]:
     @functools.wraps(f)
     def _with_cleanup(*args: typing.Any, **kwds: typing.Any) -> None: