diff --git a/block.go b/block.go
index 991c2bdf2..1352553ae 100644
--- a/block.go
+++ b/block.go
@@ -440,7 +440,7 @@ Outer:
 			if intervalOverlap(mint, maxt, chk.MinTime, chk.MaxTime) {
 				// Delete only until the current values and not beyond.
 				tmin, tmax := clampInterval(mint, maxt, chks[0].MinTime, chks[len(chks)-1].MaxTime)
-				stones.put(p.At(), Intervals{{tmin, tmax}})
+				stones.addInterval(p.At(), Interval{tmin, tmax})
 				continue Outer
 			}
 		}
diff --git a/db_test.go b/db_test.go
index 17b33bb54..f62bf0c4a 100644
--- a/db_test.go
+++ b/db_test.go
@@ -808,7 +808,7 @@ func TestTombstoneCleanFail(t *testing.T) {
 
 		// Add some some fake tombstones to trigger the compaction.
 		tomb := NewMemTombstones()
-		tomb.put(0,Intervals{{0, 1}})
+		tomb.addInterval(0, Interval{0, 1})
 		block.tombstones = tomb
 
 		db.blocks = append(db.blocks, block)
diff --git a/querier_test.go b/querier_test.go
index 7032f2f3a..51b01de1c 100644
--- a/querier_test.go
+++ b/querier_test.go
@@ -557,7 +557,7 @@ func TestBlockQuerierDelete(t *testing.T) {
 				},
 			},
 		},
-		tombstones: NewMemTombstones().put(1, Intervals{{1, 3}}).put(2, Intervals{{1, 3}, {6, 10}}).put(3, Intervals{{6, 10}}),
+		tombstones: NewMemTombstones().addInterval(1, Interval{1, 3}).addInterval(2, Interval{1, 3}, Interval{6, 10}).addInterval(3, Interval{6, 10}),
 		queries: []query{
 			{
 				mint: 2,
diff --git a/tombstones.go b/tombstones.go
index 3cf145f5c..733a81afb 100644
--- a/tombstones.go
+++ b/tombstones.go
@@ -16,14 +16,12 @@ package tsdb
 import (
 	"encoding/binary"
 	"fmt"
+	"github.com/pkg/errors"
 	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
-
 	"sync"
-
-	"github.com/pkg/errors"
 )
 
 const tombstoneFilename = "tombstones"
@@ -174,8 +172,8 @@ func (t *memTombstones) Get(ref uint64) (Intervals, error) {
 }
 
 func (t *memTombstones) Iter(f func(uint64, Intervals) error) error {
-	t.mtx.Lock()
-	defer t.mtx.Unlock()
+	t.mtx.RLock()
+	defer t.mtx.RUnlock()
 	for ref, ivs := range t.mts {
 		if err := f(ref, ivs); err != nil {
 			return err
@@ -185,16 +183,12 @@ func (t *memTombstones) Iter(f func(uint64, Intervals) error) error {
 }
 
 // addInterval to an existing memTombstones
-func (t *memTombstones) addInterval(ref uint64, itv Interval) {
-	t.mtx.Lock()
-	t.mts[ref] = t.mts[ref].add(itv)
-	t.mtx.Unlock()
-}
-
-func (t *memTombstones) put(ref uint64, itvs Intervals) *memTombstones {
+func (t *memTombstones) addInterval(ref uint64, itvs ...Interval) *memTombstones {
 	t.mtx.Lock()
 	defer t.mtx.Unlock()
-	t.mts[ref] = itvs
+	for _, itv := range itvs {
+		t.mts[ref] = t.mts[ref].add(itv)
+	}
 	return t
 }
 
diff --git a/tombstones_test.go b/tombstones_test.go
index 05483e095..62bc06818 100644
--- a/tombstones_test.go
+++ b/tombstones_test.go
@@ -41,7 +41,7 @@ func TestWriteAndReadbackTombStones(t *testing.T) {
 			dranges = dranges.add(Interval{mint, mint + rand.Int63n(1000)})
 			mint += rand.Int63n(1000) + 1
 		}
-		stones.put(ref, dranges)
+		stones.addInterval(ref, dranges...)
 	}
 
 	testutil.Ok(t, writeTombstoneFile(tmpdir, stones))
@@ -132,7 +132,6 @@ func TestMemTombstonesConcurrency(t *testing.T) {
 
 	go func() {
 		for x := 0; x < totalRuns; x++ {
-			tomb.put(uint64(x), Intervals{{int64(x), int64(x)}})
 			tomb.addInterval(uint64(x), Interval{int64(x), int64(x)})
 		}
 		wg.Done()