diff --git a/proto/map_test.go b/proto/map_test.go
new file mode 100644
index 0000000..313e879
--- /dev/null
+++ b/proto/map_test.go
@@ -0,0 +1,46 @@
+package proto_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/golang/protobuf/proto"
+	ppb "github.com/golang/protobuf/proto/proto3_proto"
+)
+
+func marshalled() []byte {
+	m := &ppb.IntMaps{}
+	for i := 0; i < 1000; i++ {
+		m.Maps = append(m.Maps, &ppb.IntMap{
+			Rtt: map[int32]int32{1: 2},
+		})
+	}
+	b, err := proto.Marshal(m)
+	if err != nil {
+		panic(fmt.Sprintf("Can't marshal %+v: %v", m, err))
+	}
+	return b
+}
+
+func BenchmarkConcurrentMapUnmarshal(b *testing.B) {
+	in := marshalled()
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			var out ppb.IntMaps
+			if err := proto.Unmarshal(in, &out); err != nil {
+				b.Errorf("Can't unmarshal ppb.IntMaps: %v", err)
+			}
+		}
+	})
+}
+
+func BenchmarkSequentialMapUnmarshal(b *testing.B) {
+	in := marshalled()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		var out ppb.IntMaps
+		if err := proto.Unmarshal(in, &out); err != nil {
+			b.Errorf("Can't unmarshal ppb.IntMaps: %v", err)
+		}
+	}
+}
diff --git a/proto/proto3_proto/proto3.proto b/proto/proto3_proto/proto3.proto
index 75d5a02..2048655 100644
--- a/proto/proto3_proto/proto3.proto
+++ b/proto/proto3_proto/proto3.proto
@@ -76,3 +76,12 @@
 message MessageWithMap {
   map<bool, bytes> byte_mapping = 1;
 }
+
+
+message IntMap {
+  map<int32, int32> rtt = 1;
+}
+
+message IntMaps {
+  repeated IntMap maps = 1;
+}