diff --git a/setuptools/version.py b/setuptools/version.py
index 75b2a14959..c99f7b2c05 100644
--- a/setuptools/version.py
+++ b/setuptools/version.py
@@ -1,6 +1,6 @@
 from ._importlib import metadata
 
 try:
-    __version__ = metadata.version('setuptools')
+    __version__ = metadata.version('setuptools') or 'unknown'
 except Exception:
     __version__ = 'unknown'
diff --git a/tox.ini b/tox.ini
index 2a5217339d..8a40b63fcc 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,6 +12,8 @@ setenv =
 	PYTHONWARNDEFAULTENCODING = 1
 	SETUPTOOLS_ENFORCE_DEPRECATION = 1
 commands =
+	python -c 'from pathlib import Path; p = Path("setuptools.egg-info/PKG-INFO"); print(p.read_text(encoding="utf-8") if p.exists() else "NO PKG-INFO")'  # DEBUG
+	# ^ ensure no malformed egg-info in flaky tests
 	pytest {posargs}
 usedevelop = True
 extras =