diff --git a/magic-proxy b/magic-proxy
index 50481e28..e2d0c28d 100755
--- a/magic-proxy
+++ b/magic-proxy
@@ -843,6 +843,7 @@ class ProxyingHTTPRequestHandler(http.server.BaseHTTPRequestHandler):
         """Return an HTTP error status and a message in the response body."""
         self.send_response(status)
         self.send_header("Content-Type", "text/plain; charset=utf-8")
+        self.end_headers()
         self.wfile.write(message.encode("utf-8"))