diff --git a/ocaml/networkd/lib/network_device_order.ml b/ocaml/networkd/lib/network_device_order.ml
index 3231633304..da056cae84 100644
--- a/ocaml/networkd/lib/network_device_order.ml
+++ b/ocaml/networkd/lib/network_device_order.ml
@@ -65,11 +65,11 @@ module Pciaddr = struct
 
   let compare t1 t2 =
     let open Xcp_pci in
-    let ( <?> ) a b = if a = 0 then b else a in
+    let ( <?> ) a b = if a = 0 then Lazy.force b else a in
     compare t1.domain t2.domain
-    <?> compare t1.bus t2.bus
-    <?> compare t1.dev t2.dev
-    <?> compare t1.fn t2.fn
+    <?> lazy (compare t1.bus t2.bus)
+    <?> lazy (compare t1.dev t2.dev)
+    <?> lazy (compare t1.fn t2.fn)
 end
 
 module Macaddr = struct