diff --git a/server/app/api/proxy/[[...path]]/route.ts b/server/app/api/proxy/[[...path]]/route.ts
index 7150582..0fcaf50 100644
--- a/server/app/api/proxy/[[...path]]/route.ts
+++ b/server/app/api/proxy/[[...path]]/route.ts
@@ -42,13 +42,13 @@ async function proxyRequest(req: NextRequest) {
   headers.set("x-forwarded-port", "443");
   headers.set("x-forwarded-for", req.headers.get("x-forwarded-for") || "unknown");
 
+  const needsBody = req.method !== "GET" && req.method !== "HEAD";
   const upstreamRes = await fetch(upstream, {
     method: req.method,
     headers,
-    body:
-      req.method !== "GET" && req.method !== "HEAD"
-        ? (req.body as BodyInit)
-        : undefined,
+    body: needsBody ? (req.body as BodyInit) : undefined,
+    // Node.js fetch requires duplex when forwarding a request body stream
+    ...(needsBody ? { duplex: "half" } : {}),
     redirect: "manual",
   });