diff --git a/promql/engine_test.go b/promql/engine_test.go
index ea19641ba..5094df2a2 100644
--- a/promql/engine_test.go
+++ b/promql/engine_test.go
@@ -684,6 +684,7 @@ load 10s
 			Result: Matrix{
 				Series{
 					Points: []Point{{V: 1, T: 0}, {V: 1, T: 1000}, {V: 1, T: 2000}},
+					Metric: labels.EmptyLabels(),
 				},
 			},
 			Start:    time.Unix(0, 0),
@@ -4008,7 +4009,7 @@ func TestSparseHistogram_Sum_Count_AddOperator(t *testing.T) {
 			// sum().
 			queryString := fmt.Sprintf("sum(%s)", seriesName)
 			queryAndCheck(queryString, []Sample{
-				{Point{T: ts, H: &c.expected}, labels.Labels{}},
+				{Point{T: ts, H: &c.expected}, labels.EmptyLabels()},
 			})
 
 			// + operator.
@@ -4017,13 +4018,13 @@ func TestSparseHistogram_Sum_Count_AddOperator(t *testing.T) {
 				queryString += fmt.Sprintf(` + ignoring(idx) %s{idx="%d"}`, seriesName, idx)
 			}
 			queryAndCheck(queryString, []Sample{
-				{Point{T: ts, H: &c.expected}, labels.Labels{}},
+				{Point{T: ts, H: &c.expected}, labels.EmptyLabels()},
 			})
 
 			// count().
 			queryString = fmt.Sprintf("count(%s)", seriesName)
 			queryAndCheck(queryString, []Sample{
-				{Point{T: ts, V: 3}, labels.Labels{}},
+				{Point{T: ts, V: 3}, labels.EmptyLabels()},
 			})
 		})
 	}
diff --git a/promql/test.go b/promql/test.go
index 344c59c07..78cc1e9fb 100644
--- a/promql/test.go
+++ b/promql/test.go
@@ -202,7 +202,7 @@ func (t *Test) parseEval(lines []string, i int) (int, *evalCmd, error) {
 			break
 		}
 		if f, err := parseNumber(defLine); err == nil {
-			cmd.expect(0, labels.EmptyLabels(), parser.SequenceValue{Value: f})
+			cmd.expect(0, parser.SequenceValue{Value: f})
 			break
 		}
 		metric, vals, err := parser.ParseSeriesDesc(defLine)
@@ -218,7 +218,7 @@ func (t *Test) parseEval(lines []string, i int) (int, *evalCmd, error) {
 		if len(vals) > 1 {
 			return i, nil, raise(i, "expecting multiple values in instant evaluation not allowed")
 		}
-		cmd.expect(j, metric, vals...)
+		cmd.expectMetric(j, metric, vals...)
 	}
 	return i, cmd, nil
 }
@@ -368,13 +368,15 @@ func (ev *evalCmd) String() string {
 	return "eval"
 }
 
-// expect adds a new metric with a sequence of values to the set of expected
+// expect adds a sequence of values to the set of expected
 // results for the query.
-func (ev *evalCmd) expect(pos int, m labels.Labels, vals ...parser.SequenceValue) {
-	if m.IsEmpty() {
-		ev.expected[0] = entry{pos: pos, vals: vals}
-		return
-	}
+func (ev *evalCmd) expect(pos int, vals ...parser.SequenceValue) {
+	ev.expected[0] = entry{pos: pos, vals: vals}
+}
+
+// expectMetric adds a new metric with a sequence of values to the set of expected
+// results for the query.
+func (ev *evalCmd) expectMetric(pos int, m labels.Labels, vals ...parser.SequenceValue) {
 	h := m.Hash()
 	ev.metrics[h] = m
 	ev.expected[h] = entry{pos: pos, vals: vals}
diff --git a/promql/test_test.go b/promql/test_test.go
index c5cb41ed9..347f66916 100644
--- a/promql/test_test.go
+++ b/promql/test_test.go
@@ -127,11 +127,11 @@ func TestLazyLoader_WithSamplesTill(t *testing.T) {
 				require.NoError(t, err)
 				for _, s := range tc.series {
 					var matchers []*labels.Matcher
-					for _, label := range s.Metric {
+					s.Metric.Range(func(label labels.Label) {
 						m, err := labels.NewMatcher(labels.MatchEqual, label.Name, label.Value)
 						require.NoError(t, err)
 						matchers = append(matchers, m)
-					}
+					})
 
 					// Get the series for the matcher.
 					ss := querier.Select(false, nil, matchers...)