diff --git a/metropolis/test/nanoswitch/nanoswitch.go b/metropolis/test/nanoswitch/nanoswitch.go
index b491c7b..3f4fd93 100644
--- a/metropolis/test/nanoswitch/nanoswitch.go
+++ b/metropolis/test/nanoswitch/nanoswitch.go
@@ -196,7 +196,7 @@
 // nftables)
 func nfifname(n string) []byte {
 	b := make([]byte, 16)
-	copy(b, []byte(n+"\x00"))
+	copy(b, n+"\x00")
 	return b
 }