diff --git a/plugins/ndf/scripts/tests/test_usage_capture.py b/plugins/ndf/scripts/tests/test_usage_capture.py
index e2445b953..7d8226f42 100644
--- a/plugins/ndf/scripts/tests/test_usage_capture.py
+++ b/plugins/ndf/scripts/tests/test_usage_capture.py
@@ -94,6 +94,8 @@ def fake_clis(tmp_path, monkeypatch):
     monkeypatch.setenv("HOME", str(home))
     monkeypatch.setenv("CODEX_HOME", str(home / ".codex"))
     monkeypatch.setenv("SECRET_TOKEN", SECRET)
+    for name in ("NDF_USAGE_SOURCE", "NDF_USAGE_KIND", "NDF_USAGE_PLAN", "NDF_USAGE_STEP"):
+        monkeypatch.delenv(name, raising=False)  # supervise の中で走らせても名乗りを持ち込まない
     return tmp_path