diff --git a/src/docker-setup.test.ts b/src/docker-setup.test.ts
index f0644857b..25143a972 100644
--- a/src/docker-setup.test.ts
+++ b/src/docker-setup.test.ts
@@ -32,6 +32,56 @@ exit 0
 }
 
 describe("docker-setup.sh", () => {
+  it("handles unset optional env vars under strict mode", async () => {
+    const assocCheck = spawnSync("bash", ["-c", "declare -A _t=()"], {
+      encoding: "utf8",
+    });
+    if (assocCheck.status !== 0) {
+      return;
+    }
+
+    const rootDir = await mkdtemp(join(tmpdir(), "clawdbot-docker-setup-"));
+    const scriptPath = join(rootDir, "docker-setup.sh");
+    const dockerfilePath = join(rootDir, "Dockerfile");
+    const composePath = join(rootDir, "docker-compose.yml");
+    const binDir = join(rootDir, "bin");
+    const logPath = join(rootDir, "docker-stub.log");
+
+    const script = await readFile(join(repoRoot, "docker-setup.sh"), "utf8");
+    await writeFile(scriptPath, script, { mode: 0o755 });
+    await writeFile(dockerfilePath, "FROM scratch\n");
+    await writeFile(
+      composePath,
+      "services:\n  clawdbot-gateway:\n    image: noop\n  clawdbot-cli:\n    image: noop\n",
+    );
+    await writeDockerStub(binDir, logPath);
+
+    const env = {
+      ...process.env,
+      PATH: `${binDir}:${process.env.PATH ?? ""}`,
+      DOCKER_STUB_LOG: logPath,
+      CLAWDBOT_GATEWAY_TOKEN: "test-token",
+      CLAWDBOT_CONFIG_DIR: join(rootDir, "config"),
+      CLAWDBOT_WORKSPACE_DIR: join(rootDir, "clawd"),
+    };
+    delete env.CLAWDBOT_DOCKER_APT_PACKAGES;
+    delete env.CLAWDBOT_EXTRA_MOUNTS;
+    delete env.CLAWDBOT_HOME_VOLUME;
+
+    const result = spawnSync("bash", [scriptPath], {
+      cwd: rootDir,
+      env,
+      encoding: "utf8",
+    });
+
+    expect(result.status).toBe(0);
+
+    const envFile = await readFile(join(rootDir, ".env"), "utf8");
+    expect(envFile).toContain("CLAWDBOT_DOCKER_APT_PACKAGES=");
+    expect(envFile).toContain("CLAWDBOT_EXTRA_MOUNTS=");
+    expect(envFile).toContain("CLAWDBOT_HOME_VOLUME=");
+  });
+
   it("plumbs CLAWDBOT_DOCKER_APT_PACKAGES into .env and docker build args", async () => {
     const assocCheck = spawnSync("bash", ["-c", "declare -A _t=()"], {
       encoding: "utf8",