diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 662dff0c..6a7e9bac 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -42,7 +42,7 @@ jobs:
     - name: Install the project
       run: pip install --no-binary=wheel .
     - name: Install test dependencies
-      run: pip install .[test] coverage[toml]
+      run: pip install .[test] coverage[toml] build flit
     - name: Test with pytest
       run: |
         coverage run -m pytest -W always
diff --git a/tests/test_sdist.py b/tests/test_sdist.py
new file mode 100644
index 00000000..07df95af
--- /dev/null
+++ b/tests/test_sdist.py
@@ -0,0 +1,48 @@
+import os
+import subprocess
+import sys
+import tarfile
+from pathlib import Path
+
+import pytest
+
+pytest.importorskip("flit")
+pytest.importorskip("build")
+
+# This test must be run from the source directory - okay to skip if not
+DIR = os.path.abspath(os.path.dirname(__file__))
+MAIN_DIR = os.path.dirname(DIR)
+
+
+def test_compare_sdists(monkeypatch, tmpdir):
+    monkeypatch.chdir(MAIN_DIR)
+
+    sdist_build_dir = os.path.join(str(tmpdir), "bdir")
+
+    subprocess.run(
+        [
+            sys.executable,
+            "-m",
+            "build",
+            "--sdist",
+            "--no-isolation",
+            f"--outdir={sdist_build_dir}",
+        ],
+        check=True,
+    )
+
+    (sdist_build,) = Path(sdist_build_dir).glob("*.tar.gz")
+
+    # Flit doesn't allow targeting directories, as far as I can tell
+    subprocess.run(
+        [sys.executable, "-m", "flit", "build", "--format=sdist"], check=True
+    )
+
+    (sdist_flit,) = Path("dist").glob("*.tar.gz")
+
+    out = [set(), set()]
+    for i, sdist in enumerate([sdist_build, sdist_flit]):
+        with tarfile.open(str(sdist), "r:gz") as tar:
+            out[i] = set(tar.getnames())
+
+    assert out[0] == (out[1] - {"setup.py"})
diff --git a/tox.ini b/tox.ini
index e7283981..ba6bdb15 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,7 +4,7 @@
 # and then run "tox" from this directory.
 
 [tox]
-envlist = py37, py38, py39, py310, py311, pypy3, lint
+envlist = py37, py38, py39, py310, py311, pypy3, lint, pkg
 minversion = 3.3.0
 skip_missing_interpreters = true
 isolated_build = true
@@ -20,3 +20,10 @@ basepython = python3
 deps = pre-commit
 commands = pre-commit run --all-files --show-diff-on-failure
 skip_install = true
+
+[testenv:pkg]
+basepython = python3
+deps =
+    build
+    flit
+commands = {envpython} -b -m pytest tests/test_sdist.py {posargs}