diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2541ddd9e543..5dd139355777 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -122,7 +122,7 @@ jobs:
           # pypy3-3.8 and pypy3-3.9 -- both of them show up as 7.3.11.
           key: ${{ matrix.PYTHON.VERSION }}-${{ steps.setup-python.outputs.python-version }}-${{ matrix.PYTHON.NOXSESSION }}-${{ env.OPENSSL_HASH }}
 
-      - run: python -m pip install -c ci-constraints-requirements.txt 'nox'
+      - run: python -m pip install -c ci-constraints-requirements.txt 'nox' 'tomli; python_version < "3.11"'
       - name: Create nox environment
         run: |
             nox -v --install-only
@@ -196,7 +196,7 @@ jobs:
       - run: |
           echo "OPENSSL_FORCE_FIPS_MODE=1" >> $GITHUB_ENV
         if: matrix.IMAGE.FIPS
-      - run: /venv/bin/python -m pip install -c ci-constraints-requirements.txt 'nox'
+      - run: /venv/bin/python -m pip install -c ci-constraints-requirements.txt 'nox' 'tomli; python_version < "3.11"'
       - run: '/venv/bin/nox -v --install-only'
         env:
           CARGO_TARGET_DIR: ${{ format('{0}/src/rust/target/', github.workspace) }}
@@ -247,7 +247,7 @@ jobs:
           cache-dependency-path: ci-constraints-requirements.txt
       - run: rustup component add llvm-tools-preview
 
-      - run: python -m pip install -c ci-constraints-requirements.txt 'nox'
+      - run: python -m pip install -c ci-constraints-requirements.txt 'nox' 'tomli; python_version < "3.11"'
 
       - name: Clone wycheproof
         timeout-minutes: 2
@@ -310,7 +310,7 @@ jobs:
         timeout-minutes: 2
         with:
           key: ${{ matrix.PYTHON.NOXSESSION }}-${{ matrix.WINDOWS.ARCH }}-${{ steps.setup-python.outputs.python-version }}
-      - run: python -m pip install -c ci-constraints-requirements.txt "nox"
+      - run: python -m pip install -c ci-constraints-requirements.txt "nox" "tomli; python_version < '3.11'"
 
       - uses: dawidd6/action-download-artifact@268677152d06ba59fcec7a7f0b5d961b6ccd7e1e # v2.28.0
         with:
diff --git a/noxfile.py b/noxfile.py
index a8b10a6fbf25..05cfdd70abf0 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -14,6 +14,11 @@
 
 import nox
 
+try:
+    import tomllib
+except ImportError:
+    import tomli as tomllib  # type: ignore[import-not-found,no-redef]
+
 nox.options.reuse_existing_virtualenvs = True
 
 
@@ -27,6 +32,11 @@ def install(session: nox.Session, *args: str) -> None:
     )
 
 
+def load_pyproject_toml() -> dict:
+    with (pathlib.Path(__file__).parent / "pyproject.toml").open("rb") as f:
+        return tomllib.load(f)
+
+
 @nox.session
 @nox.session(name="tests-ssh")
 @nox.session(name="tests-randomorder")
@@ -152,22 +162,16 @@ def docs_linkcheck(session: nox.Session) -> None:
 
 @nox.session
 def flake(session: nox.Session) -> None:
-    # Just install the dependencies needed for these tests - basically
-    # `pip install .[pep8test,test,ssh,nox]`, but without installing `.`
     # TODO: Ideally there'd be a pip flag to install just our dependencies,
     # but not install us.
+    pyproject_data = load_pyproject_toml()
     install(
         session,
-        "setuptools-rust",
-        "cffi>=1.12; platform_python_implementation != 'PyPy'",
-        "wheel",
-        "ruff",
-        "check-sdist",
-        "mypy",
-        "bcrypt",
-        "click",
-        "pytest",
-        "nox",
+        *pyproject_data["build-system"]["requires"],
+        *pyproject_data["project"]["optional-dependencies"]["pep8test"],
+        *pyproject_data["project"]["optional-dependencies"]["test"],
+        *pyproject_data["project"]["optional-dependencies"]["ssh"],
+        *pyproject_data["project"]["optional-dependencies"]["nox"],
     )
     install(session, "-e", "vectors/")
 
@@ -198,10 +202,10 @@ def rust(session: nox.Session) -> None:
         }
     )
 
-    # Just install the dependencies needed for the Rust build.rs
     # TODO: Ideally there'd be a pip flag to install just our dependencies,
     # but not install us.
-    install(session, "cffi", "setuptools")
+    pyproject_data = load_pyproject_toml()
+    install(session, *pyproject_data["build-system"]["requires"])
 
     with session.chdir("src/rust/"):
         session.run("cargo", "fmt", "--all", "--", "--check", external=True)