diff --git a/lib/agent.js b/lib/agent.js
index 477ff70..17f6fb3 100644
--- a/lib/agent.js
+++ b/lib/agent.js
@@ -65,7 +65,7 @@ export default class Agent {
       opts.body = JSON.stringify(body)
     }
 
-    if (opts.body !== null && typeof body.pipe !== 'function') {
+    if (opts.body && typeof body.pipe !== 'function') {
       opts.headers['Content-Length'] = Buffer.byteLength(opts.body)
     }