diff --git a/wgengine/filter/filter_test.go b/wgengine/filter/filter_test.go
index 765446fb2..3353c2807 100644
--- a/wgengine/filter/filter_test.go
+++ b/wgengine/filter/filter_test.go
@@ -1008,7 +1008,7 @@ func benchmarkFile(b *testing.B, file string, opt benchOpt) {
 	var localNets netipx.IPSetBuilder
 	pfx := []netip.Prefix{
 		netip.MustParsePrefix("100.96.14.120/32"),
-		netip.MustParsePrefix("fd7a:115c:a1e0:ab12:4843:cd96:6260:e78/32"),
+		netip.MustParsePrefix("fd7a:115c:a1e0:ab12:4843:cd96:6260:e78/128"),
 	}
 	for _, p := range pfx {
 		localNets.AddPrefix(p)