diff --git a/tests/read-guard.test.cjs b/tests/read-guard.test.cjs
index 55f0df08d..5fa545787 100644
--- a/tests/read-guard.test.cjs
+++ b/tests/read-guard.test.cjs
@@ -29,7 +29,7 @@ const HOOK_PATH = path.join(__dirname, '..', 'hooks', 'gsd-read-guard.js');
 function runHook(payload, envOverrides = {}) {
   const input = JSON.stringify(payload);
   // Sanitize CLAUDE_SESSION_ID so positive-path tests work inside Claude Code sessions
-  const env = { ...process.env, CLAUDE_SESSION_ID: '', ...envOverrides };
+  const env = { ...process.env, CLAUDE_SESSION_ID: '', CLAUDECODE: '', ...envOverrides };
   try {
     const stdout = execFileSync(process.execPath, [HOOK_PATH], {
       input,