diff --git a/promql/test.go b/promql/test.go
index e48cad196..f8203771f 100644
--- a/promql/test.go
+++ b/promql/test.go
@@ -654,6 +654,9 @@ func (ll *LazyLoader) appendTill(ts int64) error {
 			if _, err := app.Add(m, s.T, s.V); err != nil {
 				return err
 			}
+			if i == len(smpls)-1 {
+				ll.loadCmd.defs[h] = nil
+			}
 		}
 	}
 	return app.Commit()
diff --git a/promql/test_test.go b/promql/test_test.go
new file mode 100644
index 000000000..995090382
--- /dev/null
+++ b/promql/test_test.go
@@ -0,0 +1,157 @@
+// Copyright 2019 The Prometheus Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package promql
+
+import (
+	"github.com/prometheus/prometheus/pkg/labels"
+	"math"
+	"testing"
+	"time"
+
+	"github.com/prometheus/prometheus/util/testutil"
+)
+
+func TestLazyLoader_WithSamplesTill(t *testing.T) {
+	type testCase struct {
+		ts             time.Time
+		series         []Series // Each series is checked separately. Need not mention all series here.
+		checkOnlyError bool     // If this is true, series is not checked.
+	}
+
+	cases := []struct {
+		loadString string
+		// These testCases are run in sequence. So the testCase being run is dependant on the previous testCase.
+		testCases []testCase
+	}{
+		{
+			loadString: `
+				load 10s
+					metric1 1+1x10
+			`,
+			testCases: []testCase{
+				testCase{
+					ts: time.Unix(40, 0),
+					series: []Series{
+						Series{
+							Metric: labels.FromStrings("__name__", "metric1"),
+							Points: []Point{
+								{0, 1}, {10000, 2}, {20000, 3}, {30000, 4}, {40000, 5},
+							},
+						},
+					},
+				},
+				testCase{
+					ts: time.Unix(10, 0),
+					series: []Series{
+						Series{
+							Metric: labels.FromStrings("__name__", "metric1"),
+							Points: []Point{
+								{0, 1}, {10000, 2}, {20000, 3}, {30000, 4}, {40000, 5},
+							},
+						},
+					},
+				},
+				testCase{
+					ts: time.Unix(60, 0),
+					series: []Series{
+						Series{
+							Metric: labels.FromStrings("__name__", "metric1"),
+							Points: []Point{
+								{0, 1}, {10000, 2}, {20000, 3}, {30000, 4}, {40000, 5}, {50000, 6}, {60000, 7},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			loadString: `
+				load 10s
+					metric1 1+0x5
+					metric2 1+1x100
+			`,
+			testCases: []testCase{
+				testCase{ // Adds all samples of metric1.
+					ts: time.Unix(70, 0),
+					series: []Series{
+						Series{
+							Metric: labels.FromStrings("__name__", "metric1"),
+							Points: []Point{
+								{0, 1}, {10000, 1}, {20000, 1}, {30000, 1}, {40000, 1}, {50000, 1},
+							},
+						},
+						Series{
+							Metric: labels.FromStrings("__name__", "metric2"),
+							Points: []Point{
+								{0, 1}, {10000, 2}, {20000, 3}, {30000, 4}, {40000, 5}, {50000, 6}, {60000, 7}, {70000, 8},
+							},
+						},
+					},
+				},
+				testCase{ // This tests fix for https://github.com/prometheus/prometheus/issues/5064.
+					ts:             time.Unix(300, 0),
+					checkOnlyError: true,
+				},
+			},
+		},
+	}
+
+	for _, c := range cases {
+		suite, err := NewLazyLoader(t, c.loadString)
+		testutil.Ok(t, err)
+		defer suite.Close()
+
+		for _, tc := range c.testCases {
+			suite.WithSamplesTill(tc.ts, func(err error) {
+				testutil.Ok(t, err)
+				if tc.checkOnlyError {
+					return
+				}
+
+				// Check the series.
+				queryable := suite.Queryable()
+				querier, err := queryable.Querier(suite.Context(), math.MinInt64, math.MaxInt64)
+				testutil.Ok(t, err)
+				for _, s := range tc.series {
+					var matchers []*labels.Matcher
+					for _, label := range s.Metric {
+						m, err := labels.NewMatcher(labels.MatchEqual, label.Name, label.Value)
+						testutil.Ok(t, err)
+						matchers = append(matchers, m)
+					}
+
+					// Get the series for the matcher.
+					ss, err, _ := querier.Select(nil, matchers...)
+					testutil.Ok(t, err)
+					testutil.Assert(t, ss.Next(), "")
+					storageSeries := ss.At()
+					testutil.Assert(t, !ss.Next(), "Expecting only 1 series")
+
+					// Convert `storage.Series` to `promql.Series`.
+					got := Series{
+						Metric: storageSeries.Labels(),
+					}
+					it := storageSeries.Iterator()
+					for it.Next() {
+						t, v := it.At()
+						got.Points = append(got.Points, Point{T: t, V: v})
+					}
+					testutil.Ok(t, it.Err())
+
+					testutil.Equals(t, s, got)
+				}
+			})
+		}
+	}
+}