diff --git a/txupnp/constants.py b/txupnp/constants.py
index 1a5ca1f..5e9d8c8 100644
--- a/txupnp/constants.py
+++ b/txupnp/constants.py
@@ -25,6 +25,8 @@ service_types = [
 SSDP_IP_ADDRESS = '239.255.255.250'
 SSDP_PORT = 1900
 SSDP_DISCOVER = "ssdp:discover"
+SSDP_ALL = "ssdp:all"
+
 M_SEARCH_TEMPLATE = "\r\n".join([
     "M-SEARCH * HTTP/1.1",
     "HOST: {}:{}",
diff --git a/txupnp/ssdp.py b/txupnp/ssdp.py
index 53139b8..67acd31 100644
--- a/txupnp/ssdp.py
+++ b/txupnp/ssdp.py
@@ -3,7 +3,7 @@ import binascii
 from twisted.internet import defer
 from twisted.internet.protocol import DatagramProtocol
 from txupnp.fault import UPnPError
-from txupnp.constants import GATEWAY_SCHEMA, M_SEARCH_TEMPLATE, SSDP_DISCOVER, SSDP_IP_ADDRESS, SSDP_PORT
+from txupnp.constants import GATEWAY_SCHEMA, M_SEARCH_TEMPLATE, SSDP_DISCOVER, SSDP_IP_ADDRESS, SSDP_PORT, SSDP_ALL
 
 log = logging.getLogger(__name__)
 
@@ -75,7 +75,7 @@ class SSDPProtocol(DatagramProtocol):
         return self._sem.run(self.do_start)
 
     def send_m_search(self):
-        data = M_SEARCH_TEMPLATE.format(self.ssdp_address, self.ssdp_port, GATEWAY_SCHEMA, SSDP_DISCOVER, self.ttl)
+        data = M_SEARCH_TEMPLATE.format(self.ssdp_address, self.ssdp_port, GATEWAY_SCHEMA, SSDP_ALL, self.ttl)
         try:
             log.info("sending m-search (%i bytes) to %s:%i", len(data), self.ssdp_address, self.ssdp_port)
             self.transport.write(data.encode(), (self.ssdp_address, self.ssdp_port))