Fixed false starts

1 files changed, 6 insertions, 5 deletions

diff --git a/RSSDP/SsdpDeviceLocator.cs b/RSSDP/SsdpDeviceLocator.cs
index e2b524cf4..9a110683e 100644
--- a/RSSDP/SsdpDeviceLocator.cs
+++ b/RSSDP/SsdpDeviceLocator.cs
@@ -27,14 +27,15 @@ namespace Rssdp.Infrastructure
         /// </summary>
         public SsdpDeviceLocator(ISsdpCommunicationsServer communicationsServer)
         {
-            _CommunicationsServer = communicationsServer;
-
-            if (communicationsServer != null)
+            if (communicationsServer == null)
             {
-                // This can occur is dlna is enabled, but defined to run over https.
-                _CommunicationsServer.ResponseReceived += CommsServer_ResponseReceived;
+                throw new ArgumentNullException(nameof(communicationsServer));
             }
+            
+            _CommunicationsServer = communicationsServer;
 
+            // This can occur is dlna is enabled, but defined to run over https.
+            _CommunicationsServer.ResponseReceived += CommsServer_ResponseReceived;
             _Devices = new List<DiscoveredSsdpDevice>();
         }