diff --git a/lib/rackup/stream.rb b/lib/rackup/stream.rb
index 137f8ca..22b0a99 100644
--- a/lib/rackup/stream.rb
+++ b/lib/rackup/stream.rb
@@ -6,15 +6,16 @@
 module Rackup
   # The input stream is an IO-like object which contains the raw HTTP POST data. When applicable, its external encoding must be “ASCII-8BIT” and it must be opened in binary mode, for Ruby 1.9 compatibility. The input stream must respond to gets, each, read and rewind.
   class Stream
-    def initialize(input = nil, output = Buffered.new)
+    def initialize(input = nil, output = nil)
       @input = input
       @output = output
 
-      raise ArgumentError, "Non-writable output!" unless output.respond_to?(:write)
+      raise ArgumentError, "Non-writable output!" if output && !output.respond_to?(:write)
 
       # Will hold remaining data in `#read`.
       @buffer = nil
       @closed = false
+      @closed_read = false
     end
 
     attr :input
@@ -152,6 +153,7 @@ def flush
     end
 
     def close_read
+      @closed_read = true
       @input&.close
       @input = nil
     end
@@ -182,7 +184,7 @@ def closed?
 
     # Whether there are any output chunks remaining?
     def empty?
-      @output.empty?
+      @output ? @output.empty? : true
     end
 
     private
@@ -190,8 +192,7 @@ def empty?
     def read_next
       if @input
         return @input.read
-      else
-        @input = nil
+      elsif @closed_read
         raise IOError, "Stream is not readable, input has been closed!"
       end
     end