diff --git a/Lib/CGIHTTPServer.py b/Lib/CGIHTTPServer.py
index fa30cbd..6a259a3 100644
--- a/Lib/CGIHTTPServer.py
+++ b/Lib/CGIHTTPServer.py
@@ -35,6 +35,10 @@
 
     """
 
+    # Make rfile unbuffered -- we need to read one line and then pass
+    # the rest to a subprocess, so we can't use buffered input.
+    rbufsize = 0
+
     def do_POST(self):
         """Serve a POST request.