diff --git a/fawltydeps/packages.py b/fawltydeps/packages.py
index 88aebb91..2a86cf3a 100644
--- a/fawltydeps/packages.py
+++ b/fawltydeps/packages.py
@@ -311,7 +311,7 @@ def __init__(self, srcs: AbstractSet[PyEnvSource] = frozenset()) -> None:
         self.package_dirs: Set[Path] = {src.path for src in srcs}
 
     @classmethod
-    def find_package_dirs(cls, path: Path) -> Iterator[Path]:  # noqa: C901, PLR0912
+    def find_package_dirs(cls, path: Path, *, dprint: bool = False) -> Iterator[Path]:  # noqa: C901, PLR0912
         """Return the packages directories corresponding to the given path.
 
         The given 'path' is a user-provided directory path meant to point to
@@ -330,18 +330,31 @@ def find_package_dirs(cls, path: Path) -> Iterator[Path]:  # noqa: C901, PLR0912
         # versions X.Y that are different from the current Python version.
         found = False
 
+        def debug_print(msg: str) -> None:
+            if dprint:
+                print(msg)  # noqa: T201
+
+        bin_python = path / "bin/python"
         if sys.platform.startswith("win"):  # Check for packages on Windows
+            debug_print("    - on win")
             if (path / "Scripts" / "python.exe").is_file():
+                debug_print("      - found python.exe")
                 _site_packages = site_packages(path)
                 if _site_packages.is_dir():
+                    debug_print(f"        - found site-packages at {_site_packages}!")
                     yield _site_packages
                     found = True
             if found:
                 return
 
-        elif (path / "bin/python").is_file():  # Assume POSIX
+        elif bin_python.is_file():  # Assume POSIX
+            debug_print("    - on posix, found bin/python")
+            if bin_python.is_symlink() and hasattr(bin_python, "readlink"):
+                debug_print(f"      and points to {bin_python.readlink()!r}")
+                debug_print(f"      which exists? {bin_python.readlink().exists()!r}")
             for _site_packages in path.glob("lib/python?.*/site-packages"):
                 if _site_packages.is_dir():
+                    debug_print(f"      - found site-packages at {_site_packages}!")
                     yield _site_packages
                     found = True
             if found:
@@ -349,8 +362,10 @@ def find_package_dirs(cls, path: Path) -> Iterator[Path]:  # noqa: C901, PLR0912
 
         # Workaround for projects using PEP582:
         if path.name == "__pypackages__":
+            debug_print("    - found __pypackages__")
             for _site_packages in path.glob("?.*/lib"):
                 if _site_packages.is_dir():
+                    debug_print(f"      - found site-packages at {_site_packages}!")
                     yield _site_packages
                     found = True
             if found:
@@ -359,9 +374,12 @@ def find_package_dirs(cls, path: Path) -> Iterator[Path]:  # noqa: C901, PLR0912
         # Given path is not a python environment, but it might be _inside_ one.
         # Try again with parent directory
         if path.parent != path:
+            debug_print("    - recurse up")
             for package_dir in cls.find_package_dirs(path.parent):
+                debug_print(f"      - from parent: {package_dir}")
                 with suppress(ValueError):
                     package_dir.relative_to(path)  # ValueError if not relative
+                    debug_print("        - yield it!")
                     yield package_dir
 
     @property
@@ -381,7 +399,7 @@ def _pyenvs() -> Iterator[Tuple[CustomMapping, str]]:
         return accumulate_mappings(self.__class__, _pyenvs())
 
 
-def pyenv_sources(*pyenv_paths: Path) -> Set[PyEnvSource]:
+def pyenv_sources(*pyenv_paths: Path, dprint: bool = False) -> Set[PyEnvSource]:
     """Convert Python environment paths into PyEnvSources.
 
     Convenience helper when you want to construct a LocalPackageResolver from
@@ -389,7 +407,11 @@ def pyenv_sources(*pyenv_paths: Path) -> Set[PyEnvSource]:
     """
     ret: Set[PyEnvSource] = set()
     for path in pyenv_paths:
-        package_dirs = set(LocalPackageResolver.find_package_dirs(path))
+        if dprint:
+            print(f"Looking for package dirs under {path}")  # noqa: T201
+        package_dirs = set(LocalPackageResolver.find_package_dirs(path, dprint=dprint))
+        if dprint:
+            print(f"  Found {package_dirs!r}")  # noqa: T201
         if not package_dirs:
             logger.debug(f"Could not find a Python env at {path}!")
         ret.update(PyEnvSource(d) for d in package_dirs)
diff --git a/tests/test_real_projects.py b/tests/test_real_projects.py
index 7347e24b..50142bba 100644
--- a/tests/test_real_projects.py
+++ b/tests/test_real_projects.py
@@ -10,6 +10,7 @@
 
 import json
 import logging
+import os
 import subprocess
 import sys
 import tarfile
@@ -48,7 +49,20 @@ def verify_requirements(venv_path: Path, requirements: List[str]) -> None:
         for req in requirements
         if "python_version" not in req  # we don't know how to parse these (yet)
     }
-    resolved = LocalPackageResolver(pyenv_sources(venv_path)).lookup_packages(deps)
+    print(f"Walking virtualenv at {venv_path}:")
+    for dirpath, dirnames, filenames in os.walk(venv_path):
+        print(f"  {dirpath}:")
+        print(f"    DIRS: {dirnames!r}")
+        print(f"    FILES: {filenames!r}")
+        if (
+            dirpath.endswith("/bin")
+            and "python" in filenames
+            and hasattr(Path, "readlink")
+        ):
+            print(f"      READLINK: {Path(dirpath, "python").readlink()}")
+    resolved = LocalPackageResolver(
+        pyenv_sources(venv_path, dprint=True)
+    ).lookup_packages(deps)
     assert all(dep in resolved for dep in deps)