diff --git a/encoding/bench_test.go b/encoding/bench_test.go
index ca866c0..32c81d3 100644
--- a/encoding/bench_test.go
+++ b/encoding/bench_test.go
@@ -125,7 +125,7 @@
 }
 
 func setMap(mmap pref.Map, fd pref.FieldDescriptor, level int) {
-	fields := fd.MessageType().Fields()
+	fields := fd.Message().Fields()
 	keyDesc := fields.ByNumber(1)
 	valDesc := fields.ByNumber(2)