diff --git a/rules/ast/ast.go b/rules/ast/ast.go
index 84c4aa284..0eeb3aae4 100644
--- a/rules/ast/ast.go
+++ b/rules/ast/ast.go
@@ -17,7 +17,6 @@ import (
 	"errors"
 	"flag"
 	"fmt"
-	"hash/fnv"
 	"math"
 	"time"
 
@@ -383,23 +382,6 @@ func (node *ScalarFunctionCall) Eval(timestamp clientmodel.Timestamp) clientmode
 	return node.function.callFn(timestamp, node.args).(clientmodel.SampleValue)
 }
 
-// hashForLabels returns a hash value taken from the label/value pairs of the
-// specified labels in the metric.
-func hashForLabels(metric clientmodel.Metric, labels clientmodel.LabelNames) uint64 {
-	var result uint64
-	s := fnv.New64a()
-
-	for _, label := range labels {
-		s.Write([]byte(label))
-		s.Write([]byte{clientmodel.SeparatorByte})
-		s.Write([]byte(metric[label]))
-		result ^= s.Sum64()
-		s.Reset()
-	}
-
-	return result
-}
-
 // EvalVectorInstant evaluates a VectorNode with an instant query.
 func EvalVectorInstant(node VectorNode, timestamp clientmodel.Timestamp, storage local.Storage, queryStats *stats.TimerGroup) (Vector, error) {
 	totalEvalTimer := queryStats.GetTimer(stats.TotalEvalTime).Start()
@@ -503,7 +485,7 @@ func (node *VectorAggregation) Eval(timestamp clientmodel.Timestamp) Vector {
 	vector := node.vector.Eval(timestamp)
 	result := map[uint64]*groupedAggregation{}
 	for _, sample := range vector {
-		groupingKey := hashForLabels(sample.Metric.Metric, node.groupBy)
+		groupingKey := clientmodel.SignatureForLabels(sample.Metric.Metric, node.groupBy)
 		if groupedResult, ok := result[groupingKey]; ok {
 			if node.keepExtraLabels {
 				groupedResult.labels = labelIntersection(groupedResult.labels, sample.Metric)
@@ -879,7 +861,7 @@ func (node *VectorArithExpr) evalVectors(timestamp clientmodel.Timestamp, lhs, r
 			metric := node.resultMetric(ls, rs)
 			// Check if the same label set has been added for a many-to-one matching before.
 			if node.matchCardinality == MatchManyToOne || node.matchCardinality == MatchOneToMany {
-				insHash := hashForLabels(metric.Metric, node.includeLabels)
+				insHash := clientmodel.SignatureForLabels(metric.Metric, node.includeLabels)
 				if ihs, exists := added[hash]; exists {
 					for _, ih := range ihs {
 						if ih == insHash {
@@ -971,7 +953,7 @@ func (node *VectorArithExpr) hashForMetric(metric clientmodel.Metric) uint64 {
 			}
 		}
 	}
-	return hashForLabels(metric, labels)
+	return clientmodel.SignatureForLabels(metric, labels)
 }
 
 // Eval implements the MatrixNode interface and returns the value of
diff --git a/rules/ast/functions.go b/rules/ast/functions.go
index 3a207b976..79908cd5b 100644
--- a/rules/ast/functions.go
+++ b/rules/ast/functions.go
@@ -504,7 +504,7 @@ func histogramQuantileImpl(timestamp clientmodel.Timestamp, args []Node) interfa
 	q := args[0].(ScalarNode).Eval(timestamp)
 	inVec := args[1].(VectorNode).Eval(timestamp)
 	outVec := Vector{}
-	fpToMetricWithBuckets := map[clientmodel.Fingerprint]*metricWithBuckets{}
+	signatureToMetricWithBuckets := map[uint64]*metricWithBuckets{}
 	for _, el := range inVec {
 		upperBound, err := strconv.ParseFloat(
 			string(el.Metric.Metric[clientmodel.BucketLabel]), 64,
@@ -514,18 +514,18 @@ func histogramQuantileImpl(timestamp clientmodel.Timestamp, args []Node) interfa
 			// TODO(beorn7): Issue a warning somehow.
 			continue
 		}
-		fp := bucketFingerprint(el.Metric.Metric)
-		mb, ok := fpToMetricWithBuckets[fp]
+		signature := clientmodel.SignatureWithoutLabels(el.Metric.Metric, excludedLabels)
+		mb, ok := signatureToMetricWithBuckets[signature]
 		if !ok {
 			el.Metric.Delete(clientmodel.BucketLabel)
 			el.Metric.Delete(clientmodel.MetricNameLabel)
 			mb = &metricWithBuckets{el.Metric, nil}
-			fpToMetricWithBuckets[fp] = mb
+			signatureToMetricWithBuckets[signature] = mb
 		}
 		mb.buckets = append(mb.buckets, bucket{upperBound, el.Value})
 	}
 
-	for _, mb := range fpToMetricWithBuckets {
+	for _, mb := range signatureToMetricWithBuckets {
 		outVec = append(outVec, &Sample{
 			Metric:    mb.metric,
 			Value:     clientmodel.SampleValue(quantile(q, mb.buckets)),
diff --git a/rules/ast/quantile.go b/rules/ast/quantile.go
index 0f628153f..bf43c777d 100644
--- a/rules/ast/quantile.go
+++ b/rules/ast/quantile.go
@@ -14,8 +14,6 @@
 package ast
 
 import (
-	"encoding/binary"
-	"hash/fnv"
 	"math"
 	"sort"
 
@@ -24,6 +22,13 @@ import (
 
 // Helpers to calculate quantiles.
 
+// excludedLabels are the labels to exclude from signature calculation for
+// quantiles.
+var excludedLabels = map[clientmodel.LabelName]struct{}{
+	clientmodel.MetricNameLabel: struct{}{},
+	clientmodel.BucketLabel:     struct{}{},
+}
+
 type bucket struct {
 	upperBound float64
 	count      clientmodel.SampleValue
@@ -99,46 +104,3 @@ func quantile(q clientmodel.SampleValue, buckets buckets) float64 {
 	}
 	return bucketStart + (bucketEnd-bucketStart)*float64(rank/count)
 }
-
-// bucketFingerprint works like the Fingerprint method of Metric, but ignores
-// the name and the bucket label.
-func bucketFingerprint(m clientmodel.Metric) clientmodel.Fingerprint {
-	numLabels := 0
-	if len(m) > 2 {
-		numLabels = len(m) - 2
-	}
-	labelNames := make([]string, 0, numLabels)
-	maxLength := 0
-
-	for labelName, labelValue := range m {
-		if labelName == clientmodel.MetricNameLabel || labelName == clientmodel.BucketLabel {
-			continue
-		}
-		labelNames = append(labelNames, string(labelName))
-		if len(labelName) > maxLength {
-			maxLength = len(labelName)
-		}
-		if len(labelValue) > maxLength {
-			maxLength = len(labelValue)
-		}
-	}
-
-	sort.Strings(labelNames)
-
-	summer := fnv.New64a()
-	buf := make([]byte, maxLength)
-
-	for _, labelName := range labelNames {
-		labelValue := m[clientmodel.LabelName(labelName)]
-
-		copy(buf, labelName)
-		summer.Write(buf[:len(labelName)])
-		summer.Write([]byte{clientmodel.SeparatorByte})
-
-		copy(buf, labelValue)
-		summer.Write(buf[:len(labelValue)])
-		summer.Write([]byte{clientmodel.SeparatorByte})
-	}
-
-	return clientmodel.Fingerprint(binary.LittleEndian.Uint64(summer.Sum(nil)))
-}