diff --git a/lib/protocol/rack/adapter/generic.rb b/lib/protocol/rack/adapter/generic.rb
index d8d6bbe..d27a326 100644
--- a/lib/protocol/rack/adapter/generic.rb
+++ b/lib/protocol/rack/adapter/generic.rb
@@ -114,7 +114,7 @@ def unwrap_request(request, env)
 					
 					if request.respond_to?(:hijack?) and request.hijack?
 						env[RACK_IS_HIJACK] = true
-						env[RACK_HIJACK] = proc{request.hijack!.io.dup}
+						env[RACK_HIJACK] = proc{request.hijack!.io}
 					end
 					
 					# HTTP/2 prefers `:authority` over `host`, so we do this for backwards compatibility.