diff --git a/test/node-test/client-errors.js b/test/node-test/client-errors.js
index 5e495a4707c..c04f572841c 100644
--- a/test/node-test/client-errors.js
+++ b/test/node-test/client-errors.js
@@ -1120,7 +1120,7 @@ test('retry idempotent inflight', async (t) => {
 })
 
 test('invalid opts', async (t) => {
-  const p = tspl(t, { plan: 5 })
+  const p = tspl(t, { plan: 7 })
 
   const client = new Client('http://localhost:5000')
   client.request(null, (err) => {
@@ -1142,6 +1142,14 @@ test('invalid opts', async (t) => {
     p.ok(err instanceof errors.InvalidArgumentError)
     p.strictEqual(err.message, 'invalid highWaterMark')
   })
+  client.request({
+    path: '/',
+    method: 'GET',
+    highWaterMark: Number.NaN
+  }, (err) => {
+    p.ok(err instanceof errors.InvalidArgumentError)
+    p.strictEqual(err.message, 'invalid highWaterMark')
+  })
 
   await p.completed
 })