diff --git a/execution/aggregate/hashaggregate.go b/execution/aggregate/hashaggregate.go
index 088dc3bd..84e7fb41 100644
--- a/execution/aggregate/hashaggregate.go
+++ b/execution/aggregate/hashaggregate.go
@@ -234,7 +234,7 @@ func (a *aggregate) initializeScalarTables(ctx context.Context) ([]aggregateTabl
 		labelsMap[lblName] = struct{}{}
 	}
 	for i := 0; i < len(series); i++ {
-		hash, _, lbls := hashMetric(builder, series[i], !a.by, a.labels, labelsMap, hashingBuf)
+		hash, lbls := hashMetric(builder, series[i], !a.by, a.labels, labelsMap, hashingBuf)
 		output, ok := outputMap[hash]
 		if !ok {
 			output = &model.Series{
diff --git a/execution/aggregate/khashaggregate.go b/execution/aggregate/khashaggregate.go
index 62cfe40a..0ea9ba95 100644
--- a/execution/aggregate/khashaggregate.go
+++ b/execution/aggregate/khashaggregate.go
@@ -184,7 +184,7 @@ func (a *kAggregate) init(ctx context.Context) error {
 		labelsMap[lblName] = struct{}{}
 	}
 	for i := 0; i < len(series); i++ {
-		hash, _, _ := hashMetric(builder, series[i], !a.by, a.labels, labelsMap, hashingBuf)
+		hash, _ := hashMetric(builder, series[i], !a.by, a.labels, labelsMap, hashingBuf)
 		h, ok := heapsHash[hash]
 		if !ok {
 			h = &samplesHeap{compare: a.compare}
diff --git a/execution/aggregate/scalar_table.go b/execution/aggregate/scalar_table.go
index 98c232fb..9173ae78 100644
--- a/execution/aggregate/scalar_table.go
+++ b/execution/aggregate/scalar_table.go
@@ -109,7 +109,7 @@ func hashMetric(
 	grouping []string,
 	groupingSet map[string]struct{},
 	buf []byte,
-) (uint64, string, labels.Labels) {
+) (uint64, labels.Labels) {
 	buf = buf[:0]
 	builder.Reset()
 
@@ -123,12 +123,12 @@ func hashMetric(
 			}
 			builder.Add(lbl.Name, lbl.Value)
 		})
-		key, bytes := metric.HashWithoutLabels(buf, grouping...)
-		return key, string(bytes), builder.Labels()
+		key, _ := metric.HashWithoutLabels(buf, grouping...)
+		return key, builder.Labels()
 	}
 
 	if len(grouping) == 0 {
-		return 0, "", labels.Labels{}
+		return 0, labels.Labels{}
 	}
 
 	metric.Range(func(lbl labels.Label) {
@@ -137,8 +137,8 @@ func hashMetric(
 		}
 		builder.Add(lbl.Name, lbl.Value)
 	})
-	key, bytes := metric.HashForLabels(buf, grouping...)
-	return key, string(bytes), builder.Labels()
+	key, _ := metric.HashForLabels(buf, grouping...)
+	return key, builder.Labels()
 }
 
 type newAccumulatorFunc func() *accumulator