diff --git a/metropolis/test/nanoswitch/nanoswitch.go b/metropolis/test/nanoswitch/nanoswitch.go
index 212696d..e44fc80 100644
--- a/metropolis/test/nanoswitch/nanoswitch.go
+++ b/metropolis/test/nanoswitch/nanoswitch.go
@@ -28,7 +28,6 @@
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"os"
 	"time"
@@ -302,7 +301,7 @@
 			dhcpClient.RequestedOptions = []dhcpv4.OptionCode{dhcpv4.OptionRouter}
 			dhcpClient.LeaseCallback = dhcpcb.Compose(dhcpcb.ManageIP(externalLink), dhcpcb.ManageDefaultRoute(externalLink))
 			supervisor.Run(ctx, "dhcp-client", dhcpClient.Run)
-			if err := ioutil.WriteFile("/proc/sys/net/ipv4/ip_forward", []byte("1\n"), 0644); err != nil {
+			if err := os.WriteFile("/proc/sys/net/ipv4/ip_forward", []byte("1\n"), 0644); err != nil {
 				logger.Fatalf("Failed to write ip forwards: %v", err)
 			}
 		} else {