services: Use the correct invalid handle value for the control pipe.
diff --git a/programs/services/rpc.c b/programs/services/rpc.c
index 3f6ee40..baeab19 100644
--- a/programs/services/rpc.c
+++ b/programs/services/rpc.c
@@ -827,7 +827,7 @@
     if (dwControl == SERVICE_CONTROL_STOP)
     {
         service->service_entry->control_mutex = NULL;
-        service->service_entry->control_pipe = NULL;
+        service->service_entry->control_pipe = INVALID_HANDLE_VALUE;
     }
 
     service_unlock(service->service_entry);