diff --git a/gns3server/utils/asyncio/telnet_server.py b/gns3server/utils/asyncio/telnet_server.py
index 2e736410..604ab914 100644
--- a/gns3server/utils/asyncio/telnet_server.py
+++ b/gns3server/utils/asyncio/telnet_server.py
@@ -322,6 +322,7 @@ class AsyncioTelnetServer:
         else:
             log.debug("Not supported negotiation sequence, received {} bytes", len(data))
 
+    @asyncio.coroutine
     def _IAC_parser(self, buf, network_reader, network_writer, connection):
         """
         Processes and removes any Telnet commands from the buffer.