diff --git a/mempalace/__init__.py b/mempalace/__init__.py
index a2ce132..9db4124 100644
--- a/mempalace/__init__.py
+++ b/mempalace/__init__.py
@@ -9,13 +9,18 @@ def _strip_leaked_pythonpath() -> None:
     # Venvs inherit PYTHONPATH; on multi-Python systems it can cause
     # transitive imports to load compiled extensions (pydantic_core,
     # chromadb_rust_bindings) from the wrong ABI. Drop the env var
-    # and remove the sys.path entries the interpreter populated from
-    # it before the consumer imports anything that ships compiled code.
+    # and remove sys.path entries the interpreter populated from it.
+    # Comparison normalizes case + separators so Windows paths and
+    # trailing-separator quirks do not slip through string equality.
     leaked = os.environ.pop("PYTHONPATH", None)
     if not leaked:
         return
-    leaked_entries = {p for p in leaked.split(os.pathsep) if p}
-    sys.path[:] = [p for p in sys.path if p not in leaked_entries]
+
+    def _norm(path: str) -> str:
+        return os.path.normcase(os.path.normpath(path))
+
+    leaked_entries = {_norm(p.strip()) for p in leaked.split(os.pathsep) if p.strip()}
+    sys.path[:] = [p for p in sys.path if _norm(p) not in leaked_entries]
 
 
 _strip_leaked_pythonpath()
diff --git a/tests/test_init.py b/tests/test_init.py
index 643c067..cc47f8c 100644
--- a/tests/test_init.py
+++ b/tests/test_init.py
@@ -7,18 +7,25 @@ import sys
 import pytest
 
 
+_LEAK_PREFIX = "/__mempalace_leak_test_sentinel__"
+
+
 @pytest.mark.parametrize(
     "pythonpath",
     [
-        "/tmp/some/leaked/path",
-        f"/tmp/leak-a{os.pathsep}/tmp/leak-b",
+        f"{_LEAK_PREFIX}/single",
+        f"{_LEAK_PREFIX}/a{os.pathsep}{_LEAK_PREFIX}/b",
+        f"{_LEAK_PREFIX}/with-trailing{os.sep}",
+        f"{os.pathsep}{_LEAK_PREFIX}/leading-sep",
+        "",
         None,
     ],
+    ids=["single", "multi", "trailing-sep", "leading-pathsep", "empty", "unset"],
 )
 def test_init_strips_leaked_pythonpath(pythonpath):
-    """Package init must clear PYTHONPATH (env) AND remove its entries
-    from sys.path so compiled-extension imports cannot resolve from a
-    leaked location."""
+    """Package init must clear PYTHONPATH (env) AND remove all of its
+    leaked entries from sys.path, normalizing case and trailing
+    separators so Windows and POSIX behave alike."""
     env = os.environ.copy()
     if pythonpath is None:
         env.pop("PYTHONPATH", None)
@@ -28,8 +35,11 @@ def test_init_strips_leaked_pythonpath(pythonpath):
         "import mempalace, os, sys; "
         f"leaked = {pythonpath!r}; "
         "print('ENV:', repr(os.environ.get('PYTHONPATH'))); "
-        "entries = leaked.split(os.pathsep) if leaked else []; "
-        "leaked_in_path = any(e in sys.path for e in entries); "
+        "tokens = leaked.split(os.pathsep) if leaked else []; "
+        "entries = [t.strip() for t in tokens if t.strip()]; "
+        "norm = lambda p: os.path.normcase(os.path.normpath(p)); "
+        "leaked_norm = {norm(e) for e in entries}; "
+        "leaked_in_path = any(norm(p) in leaked_norm for p in sys.path); "
         "print('SYSPATH_LEAK:', leaked_in_path)"
     )
     result = subprocess.run(
@@ -37,10 +47,13 @@ def test_init_strips_leaked_pythonpath(pythonpath):
         env=env,
         capture_output=True,
         text=True,
-        check=True,
+        check=False,
     )
+    diag = (
+        f"input={pythonpath!r}; rc={result.returncode}; "
+        f"stdout={result.stdout!r}; stderr={result.stderr!r}"
+    )
+    assert result.returncode == 0, f"subprocess failed: {diag}"
     out = result.stdout
-    assert "ENV: None" in out, f"PYTHONPATH not cleared (input={pythonpath!r}): {out!r}"
-    assert (
-        "SYSPATH_LEAK: False" in out
-    ), f"sys.path retains leaked entry (input={pythonpath!r}): {out!r}"
+    assert "ENV: None" in out, f"PYTHONPATH not cleared: {diag}"
+    assert "SYSPATH_LEAK: False" in out, f"sys.path retains leaked entry: {diag}"