diff --git a/lib/api/api-request.js b/lib/api/api-request.js
index 1d56fb0c9ad..20487761a83 100644
--- a/lib/api/api-request.js
+++ b/lib/api/api-request.js
@@ -21,7 +21,7 @@ class RequestHandler extends AsyncResource {
         throw new InvalidArgumentError('invalid callback')
       }
 
-      if (highWaterMark && (typeof highWaterMark !== 'number' || highWaterMark < 0)) {
+      if (highWaterMark != null && (!Number.isFinite(highWaterMark) || highWaterMark < 0)) {
         throw new InvalidArgumentError('invalid highWaterMark')
       }
 
diff --git a/test/node-test/client-errors.js b/test/node-test/client-errors.js
index 4021bb37955..d260f628b85 100644
--- a/test/node-test/client-errors.js
+++ b/test/node-test/client-errors.js
@@ -1161,7 +1161,7 @@ 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) => {
@@ -1186,6 +1186,14 @@ 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
 })