diff --git a/test/labels-dispatch.test.sh b/test/labels-dispatch.test.sh
index 90a1e6c..d7c3bf4 100755
--- a/test/labels-dispatch.test.sh
+++ b/test/labels-dispatch.test.sh
@@ -136,7 +136,13 @@ check "any non-204 fails, not only the statuses the API documents" 1 "forbidden"
 run_step_no_api() {
   rm -rf "${TMP:?}/bin"; mkdir -p "$TMP/bin"; : >"$TMP/calls"
   make_curl 204 ""
-  env PATH="$TMP/bin:$PATH" GITHUB_TOKEN=tok GITHUB_REPOSITORY=owner/repo \
+  # -u, because plain `env` PRESERVES the parent environment: on the runner
+  # every step arrives with GITHUB_API_URL set — the premise of the fix under
+  # test — so without the unset this case inherits it, the refusal path never
+  # executes, and the case passes only in a dev shell that lacks the variable
+  # (@kimi-reviewer-andresmgsl, run 468).
+  env -u GITHUB_API_URL \
+    PATH="$TMP/bin:$PATH" GITHUB_TOKEN=tok GITHUB_REPOSITORY=owner/repo \
     SWEEP_WORKFLOW=self-labels-sweep.yml DEFAULT_BRANCH=main "$STEP"
 }
 check "an unset GITHUB_API_URL refuses rather than guessing GitHub" 1 \