socket.go     | 4 ++--
 utp_libutp.go | 2 +-

diff --git a/socket.go b/socket.go
index fbe8d9cb0c402e6531daea7525d8a03cf0cb8569..4de2592a094e59b52cbeb6f2685f5c97c4aab573 100644
--- a/socket.go
+++ b/socket.go
@@ -5,7 +5,6 @@ 	"context"
 	"net"
 	"strconv"
 
-	utp "github.com/anacrolix/go-libutp"
 	"github.com/anacrolix/missinggo/perf"
 	"github.com/anacrolix/missinggo/v2"
 	"github.com/pkg/errors"
@@ -101,7 +100,8 @@ 	}
 	return
 }
 
-type firewallCallback = utp.FirewallCallback
+// This isn't aliased from go-libutp since that assumes CGO.
+type firewallCallback func(net.Addr) bool
 
 func listenUtp(network, addr string, fc firewallCallback) (socket, error) {
 	us, err := NewUtpSocket(network, addr, fc)
diff --git a/utp_libutp.go b/utp_libutp.go
index 3cbd01c07985713fd1c8e7decae01143335d1048..76e530de940a8b5261c5e1ca0fd92bf0bda698f1 100644
--- a/utp_libutp.go
+++ b/utp_libutp.go
@@ -16,7 +16,7 @@ 	if err != nil {
 		return s, err
 	}
 	if fc != nil {
-		s.SetSyncFirewallCallback(fc)
+		s.SetSyncFirewallCallback(utp.FirewallCallback(fc))
 	}
 	return s, err
 }