diff --git a/topic_test.go b/topic_test.go
index 52927c0a..e236c602 100644
--- a/topic_test.go
+++ b/topic_test.go
@@ -3,6 +3,8 @@ package pubsub
 import (
 	"bytes"
 	"context"
+	"crypto/sha1"
+	"crypto/sha256"
 	"errors"
 	"fmt"
 	"math/rand"
@@ -11,6 +13,7 @@ import (
 	"time"
 
 	"github.com/libp2p/go-libp2p-core/peer"
+	pb "github.com/libp2p/go-libp2p-pubsub/pb"
 )
 
 func getTopics(psubs []*PubSub, topicID string, opts ...TopicOpt) []*Topic {
@@ -860,3 +863,60 @@ func TestMinTopicSizeNoDiscovery(t *testing.T) {
 		t.Fatal("received incorrect message")
 	}
 }
+
+func TestWithTopicMsgIdFunction(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	const topicA, topicB = "foobarA", "foobarB"
+	const numHosts = 2
+
+	hosts := getNetHosts(t, ctx, numHosts)
+	pubsubs := getPubsubs(ctx, hosts, WithMessageIdFn(func(pmsg *pb.Message) string {
+		hash := sha256.Sum256(pmsg.Data)
+		return string(hash[:])
+	}))
+	connectAll(t, hosts)
+
+	topicsA := getTopics(pubsubs, topicA) // uses global msgIdFn
+	topicsB := getTopics(pubsubs, topicB, WithTopicMessageIdFn(func(pmsg *pb.Message) string { // uses custom
+		hash := sha1.Sum(pmsg.Data)
+		return string(hash[:])
+	}))
+
+	payload := []byte("pubsub rocks")
+
+	subA, err := topicsA[0].Subscribe()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = topicsA[1].Publish(ctx, payload, WithReadiness(MinTopicSize(1)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	msgA, err := subA.Next(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	subB, err := topicsB[0].Subscribe()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = topicsB[1].Publish(ctx, payload, WithReadiness(MinTopicSize(1)))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	msgB, err := subB.Next(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if msgA.ID == msgB.ID {
+		t.Fatal("msg ids are equal")
+	}
+}