diff --git a/Naiad/Runtime/Controlling/Controller.cs b/Naiad/Runtime/Controlling/Controller.cs
index 72b4c94..17fc80e 100644
--- a/Naiad/Runtime/Controlling/Controller.cs
+++ b/Naiad/Runtime/Controlling/Controller.cs
@@ -768,6 +768,10 @@ public BaseController(Configuration config)
 
             if (this.configuration.Endpoints != null)
             {
+                if (this.configuration.ProcessID >= this.configuration.Endpoints.Length)
+                {
+                    throw new ApplicationException("Intended process number (-p) should less then the number supplied to -n");
+                }
                 endpoint = this.configuration.Endpoints[this.configuration.ProcessID];
             }