diff --git a/v2v/cmdline.ml b/v2v/cmdline.ml
index 82f9a7da6..ae7d80284 100644
--- a/v2v/cmdline.ml
+++ b/v2v/cmdline.ml
@@ -137,11 +137,11 @@ let parse_cmdline () =
                           if_prefix_length; if_nameservers }
        in
        (match String.nsplit "," out with
-        | [] | [_] ->
+        | [] ->
            error (f_"invalid --mac ip option")
-        | [mac; ip] -> add mac ip None None []
-        | [mac; ip; gw] -> add mac ip (Some gw) None []
-        | mac :: ip :: gw :: len :: nameservers ->
+        | [ip] -> add mac ip None None []
+        | [ip; gw] -> add mac ip (Some gw) None []
+        | ip :: gw :: len :: nameservers ->
            let len =
              try int_of_string len with
              | Failure _ -> error (f_"cannot parse --mac ip prefix length field as an integer: %s") len in