diff --git a/skills/fix-plan/scripts/hook_integrity_check.py b/skills/fix-plan/scripts/hook_integrity_check.py
index 5d737771..cf556e45 100644
--- a/skills/fix-plan/scripts/hook_integrity_check.py
+++ b/skills/fix-plan/scripts/hook_integrity_check.py
@@ -64,7 +64,12 @@ def resolve_script_operand(command):
     resolves to `/path/hook.sh`, not to the interpreter.
     """
     try:
-        tokens = shlex.split(command)
+        # posix=True (the default) treats backslash as an escape character,
+        # so a Windows path like C:\Users\... loses every backslash
+        # (\U -> U, \A -> A, ...) and the resolved path silently stops
+        # existing. posix=False keeps backslashes literal; the manual
+        # strip('"')/strip("'") calls below still handle quoting.
+        tokens = shlex.split(command, posix=(sys.platform != "win32"))
     except ValueError:
         tokens = command.split()
     for tok in tokens:
diff --git a/tests/test_hook_integrity_check.py b/tests/test_hook_integrity_check.py
index 39eb2416..c821ad6f 100644
--- a/tests/test_hook_integrity_check.py
+++ b/tests/test_hook_integrity_check.py
@@ -88,6 +88,24 @@ def test_resolve_plain_path_unchanged():
     assert mod.resolve_script_operand('"/p/with space/hook.sh"') == "/p/with space/hook.sh"
 
 
+def test_resolve_preserves_windows_backslashes(monkeypatch):
+    # posix=True shlex.split treats backslash as an escape character, so a
+    # Windows path silently loses every backslash (\U -> U, \A -> A, ...)
+    # and the resolved path stops existing. Guards the fix for that.
+    # Force the win32 branch explicitly so this test is deterministic
+    # regardless of the platform actually running it (CI runs on Linux).
+    monkeypatch.setattr(mod.sys, "platform", "win32")
+    assert mod.resolve_script_operand(r"python3 C:\Users\me\hook.sh") == r"C:\Users\me\hook.sh"
+
+
+def test_resolve_posix_path_unaffected_by_win32_branch(monkeypatch):
+    # On win32, posix=False is used -- confirm ordinary POSIX paths and
+    # interpreter/flag skipping still resolve correctly under that mode.
+    monkeypatch.setattr(mod.sys, "platform", "win32")
+    assert mod.resolve_script_operand("python3 /p/hook.sh") == "/p/hook.sh"
+    assert mod.resolve_script_operand('"/p/with space/hook.sh"') == "/p/with space/hook.sh"
+
+
 # --- check_hook_integrity: end-to-end on the installed schema ---
 
 def test_installed_schema_is_audited(tmp_path, monkeypatch):