diff --git a/storage/merge.go b/storage/merge.go
index c57a24c76..fca052ca1 100644
--- a/storage/merge.go
+++ b/storage/merge.go
@@ -467,6 +467,7 @@ func (c *chainSampleIterator) Seek(t int64) bool {
 	}
 	if len(c.h) > 0 {
 		c.curr = heap.Pop(&c.h).(chunkenc.Iterator)
+		c.lastt, _ = c.curr.At()
 		return true
 	}
 	c.curr = nil
diff --git a/storage/merge_test.go b/storage/merge_test.go
index 415b7fb60..2ed68879a 100644
--- a/storage/merge_test.go
+++ b/storage/merge_test.go
@@ -647,6 +647,14 @@ func TestChainSampleIteratorSeek(t *testing.T) {
 			seek:     2,
 			expected: []tsdbutil.Sample{sample{2, 2}, sample{3, 3}, sample{4, 4}, sample{5, 5}},
 		},
+		{
+			input: []chunkenc.Iterator{
+				NewListSeriesIterator(samples{sample{0, 0}, sample{2, 2}, sample{3, 3}}),
+				NewListSeriesIterator(samples{sample{0, 0}, sample{1, 1}, sample{2, 2}}),
+			},
+			seek:     0,
+			expected: []tsdbutil.Sample{sample{0, 0}, sample{1, 1}, sample{2, 2}, sample{3, 3}},
+		},
 	} {
 		merged := newChainSampleIterator(tc.input)
 		actual := []tsdbutil.Sample{}