diff --git a/test/undici/request.js b/test/undici/request.js
new file mode 100644
index 00000000000000..c1e6c7905cff2d
--- /dev/null
+++ b/test/undici/request.js
@@ -0,0 +1,19 @@
+const { test } = require('tap')
+const { Request } = require('../lib/undici/request')
+const { Readable } = require('stream')
+
+test('Request with ReadableStream body requires duplex option', (t) => {
+  t.plan(2)
+
+  const stream = new Readable({
+    read () {}
+  })
+
+  t.throws(() => {
+    new Request('http://example.com', { body: stream })
+  }, TypeError, 'should throw when duplex is missing')
+
+  t.doesNotThrow(() => {
+    new Request('http://example.com', { body: stream, duplex: 'auto' })
+  }, 'should not throw when duplex is provided')
+})
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