diff --git a/OpenOS/README.md b/OpenOS/README.md
index 2c27799..4989752 100644
--- a/OpenOS/README.md
+++ b/OpenOS/README.md
@@ -45,7 +45,7 @@ The net library provides an easy way of interacting with the minitel daemon, and
 
 *net.usend(host, port, data, pid)* - Sends an unreliable packet to *host* on *port* containing *data*, optionally with the packet ID *pid*.
 
-*net.rsend(host, port, data)* - Sends a reliable packet to *host* on *port* containing *data*.
+*net.rsend(host, port, data, block)* - Sends a reliable packet to *host* on *port* containing *data*. If *block* is true, don't wait for a reply.
 
 #### Layer 4
 
diff --git a/OpenOS/usr/lib/net.lua b/OpenOS/usr/lib/net.lua
index d8445e1..2eccf4b 100644
--- a/OpenOS/usr/lib/net.lua
+++ b/OpenOS/usr/lib/net.lua
@@ -19,9 +19,10 @@ function net.usend(to,port,data,npID)
  computer.pushSignal("net_send",0,to,port,data,npID)
 end
 
-function net.rsend(to,port,data)
+function net.rsend(to,port,data,block)
  local pid, stime = net.genPacketID(), computer.uptime() + net.streamdelay
  computer.pushSignal("net_send",1,to,port,data,pid)
+ if block then return false end
  repeat
   _,rpid = event.pull(0.5,"net_ack")
  until rpid == pid or computer.uptime() > stime