diff --git a/pre_commit/resources/hook-tmpl b/pre_commit/resources/hook-tmpl
index 3703b9b9..4bfb2398 100755
--- a/pre_commit/resources/hook-tmpl
+++ b/pre_commit/resources/hook-tmpl
@@ -57,7 +57,8 @@ def _run_legacy():
     legacy_script = HOOK_TYPE + '.legacy'
     is_legacy_executed = os.path.basename(__file__) == legacy_script
     legacy_hook = os.path.join(HERE, legacy_script)
-    if not is_legacy_executed and os.access(legacy_hook, os.X_OK):
+    assert not is_legacy_executed, __file__
+    if os.access(legacy_hook, os.X_OK):
         cmd = _norm_exe(legacy_hook) + (legacy_hook,) + tuple(sys.argv[1:])
         proc = subprocess.Popen(cmd, stdin=subprocess.PIPE if stdin else None)
         proc.communicate(stdin)