diff --git a/pkg/store/bucket_test.go b/pkg/store/bucket_test.go
index 1570caec4a..fa29c69bc5 100644
--- a/pkg/store/bucket_test.go
+++ b/pkg/store/bucket_test.go
@@ -3050,3 +3050,117 @@ func TestPostingGroupMerge(t *testing.T) {
 		})
 	}
 }
+
+// TestExpandedPostings is a test whether there is a race between multiple ExpandPostings() calls.
+func TestExpandedPostingsRace(t *testing.T) {
+	const blockCount = 10
+
+	tmpDir := t.TempDir()
+	t.Cleanup(func() {
+		testutil.Ok(t, os.RemoveAll(tmpDir))
+	})
+
+	bkt := objstore.NewInMemBucket()
+	t.Cleanup(func() {
+		testutil.Ok(t, bkt.Close())
+	})
+
+	// Create a block.
+	head, _ := storetestutil.CreateHeadWithSeries(t, 0, storetestutil.HeadGenOptions{
+		TSDBDir:          filepath.Join(tmpDir, "head"),
+		SamplesPerSeries: 10,
+		ScrapeInterval:   15 * time.Second,
+		Series:           1000,
+		PrependLabels:    nil,
+		Random:           rand.New(rand.NewSource(120)),
+		SkipChunks:       true,
+	})
+	blockID := createBlockFromHead(t, tmpDir, head)
+
+	bucketBlocks := make([]*bucketBlock, 0, blockCount)
+
+	for i := 0; i < blockCount; i++ {
+		ul := ulid.MustNew(uint64(i), rand.New(rand.NewSource(444)))
+
+		// Upload the block to the bucket.
+		thanosMeta := metadata.Thanos{
+			Labels:     labels.Labels{{Name: "ext1", Value: fmt.Sprintf("%d", i)}}.Map(),
+			Downsample: metadata.ThanosDownsample{Resolution: 0},
+			Source:     metadata.TestSource,
+		}
+		m, err := metadata.ReadFromDir(filepath.Join(tmpDir, blockID.String()))
+		testutil.Ok(t, err)
+
+		m.Thanos = thanosMeta
+		m.BlockMeta.ULID = ul
+
+		e2eutil.Copy(t, filepath.Join(tmpDir, blockID.String()), filepath.Join(tmpDir, ul.String()))
+		testutil.Ok(t, m.WriteToDir(log.NewLogfmtLogger(os.Stderr), filepath.Join(tmpDir, ul.String())))
+		testutil.Ok(t, err)
+		testutil.Ok(t, block.Upload(context.Background(), log.NewLogfmtLogger(os.Stderr), bkt, filepath.Join(tmpDir, ul.String()), metadata.NoneFunc))
+
+		r, err := indexheader.NewBinaryReader(context.Background(), log.NewNopLogger(), bkt, tmpDir, ul, DefaultPostingOffsetInMemorySampling)
+		testutil.Ok(t, err)
+
+		blk, err := newBucketBlock(
+			context.Background(),
+			log.NewLogfmtLogger(os.Stderr),
+			newBucketStoreMetrics(nil),
+			m,
+			bkt,
+			filepath.Join(tmpDir, ul.String()),
+			noopCache{},
+			nil,
+			r,
+			NewGapBasedPartitioner(PartitionerMaxGapSize),
+			nil,
+			nil,
+		)
+		testutil.Ok(t, err)
+
+		bucketBlocks = append(bucketBlocks, blk)
+	}
+
+	tm, cancel := context.WithTimeout(context.Background(), 40*time.Second)
+	t.Cleanup(cancel)
+
+	l := sync.Mutex{}
+	previousRefs := make(map[int][]storage.SeriesRef)
+
+	for {
+		if tm.Err() != nil {
+			break
+		}
+
+		m := []*labels.Matcher{
+			labels.MustNewMatcher(labels.MatchEqual, "foo", "bar"),
+			labels.MustNewMatcher(labels.MatchRegexp, "j", ".+"),
+			labels.MustNewMatcher(labels.MatchRegexp, "i", ".+"),
+			labels.MustNewMatcher(labels.MatchEqual, "foo", "bar"),
+			labels.MustNewMatcher(labels.MatchRegexp, "j", ".+"),
+			labels.MustNewMatcher(labels.MatchRegexp, "i", ".+"),
+			labels.MustNewMatcher(labels.MatchEqual, "foo", "bar"),
+		}
+
+		wg := &sync.WaitGroup{}
+		for i, bb := range bucketBlocks {
+			wg.Add(1)
+			i := i
+			bb := bb
+			go func(i int, bb *bucketBlock) {
+				refs, err := bb.indexReader().ExpandedPostings(context.Background(), m, NewBytesLimiterFactory(0)(nil))
+				testutil.Ok(t, err)
+				defer wg.Done()
+
+				l.Lock()
+				defer l.Unlock()
+				if previousRefs[i] != nil {
+					testutil.Equals(t, previousRefs[i], refs)
+				} else {
+					previousRefs[i] = refs
+				}
+			}(i, bb)
+		}
+		wg.Wait()
+	}
+}