diff --git a/pkg/logql/log/parser.go b/pkg/logql/log/parser.go
index fbd43864d4d68..9dabba488ab02 100644
--- a/pkg/logql/log/parser.go
+++ b/pkg/logql/log/parser.go
@@ -315,14 +315,18 @@ func (j *JSONExpressionParser) Process(line []byte, lbs *LabelsBuilder) ([]byte,
 
 func (j *JSONExpressionParser) RequiredLabelNames() []string { return []string{} }
 
-type UnpackParser struct{}
+type UnpackParser struct {
+	lbsBuffer []string
+}
 
 // NewUnpackParser creates a new unpack stage.
 // The unpack stage will parse a json log line as map[string]string where each key will be translated into labels.
 // A special key _entry will also be used to replace the original log line. This is to be used in conjunction with Promtail pack stage.
 // see https://grafana.com/docs/loki/latest/clients/promtail/stages/pack/
 func NewUnpackParser() *UnpackParser {
-	return &UnpackParser{}
+	return &UnpackParser{
+		lbsBuffer: make([]string, 0, 16),
+	}
 }
 
 func (UnpackParser) RequiredLabelNames() []string { return []string{} }
@@ -331,10 +335,11 @@ func (u *UnpackParser) Process(line []byte, lbs *LabelsBuilder) ([]byte, bool) {
 	if lbs.ParserLabelHints().NoLabels() {
 		return line, true
 	}
+	u.lbsBuffer = u.lbsBuffer[:0]
 	it := jsoniter.ConfigFastest.BorrowIterator(line)
 	defer jsoniter.ConfigFastest.ReturnIterator(it)
 
-	entry, err := u.unpack(it, lbs)
+	entry, err := u.unpack(it, line, lbs)
 	if err != nil {
 		lbs.SetErr(errJSON)
 		return line, true
@@ -342,12 +347,12 @@ func (u *UnpackParser) Process(line []byte, lbs *LabelsBuilder) ([]byte, bool) {
 	return entry, true
 }
 
-func (u *UnpackParser) unpack(it *jsoniter.Iterator, lbs *LabelsBuilder) ([]byte, error) {
+func (u *UnpackParser) unpack(it *jsoniter.Iterator, entry []byte, lbs *LabelsBuilder) ([]byte, error) {
 	// we only care about object and values.
 	if nextType := it.WhatIsNext(); nextType != jsoniter.ObjectValue {
 		return nil, fmt.Errorf("expecting json object(%d), got %d", jsoniter.ObjectValue, nextType)
 	}
-	var entry []byte
+	var isPacked bool
 	_ = it.ReadMapCB(func(iter *jsoniter.Iterator, field string) bool {
 		switch iter.WhatIsNext() {
 		case jsoniter.StringValue:
@@ -357,8 +362,8 @@ func (u *UnpackParser) unpack(it *jsoniter.Iterator, lbs *LabelsBuilder) ([]byte
 				// todo(ctovena): we should just reslice the original line since the property is contiguous
 				// but jsoniter doesn't allow us to do this right now.
 				// https://github.com/buger/jsonparser might do a better job at this.
-				entry = make([]byte, len(s))
-				copy(entry, s)
+				entry = append(entry[:0], s...)
+				isPacked = true
 				return true
 			}
 			if !lbs.ParserLabelHints().ShouldExtract(field) {
@@ -368,7 +373,8 @@ func (u *UnpackParser) unpack(it *jsoniter.Iterator, lbs *LabelsBuilder) ([]byte
 			if lbs.BaseHas(field) {
 				field = field + duplicateSuffix
 			}
-			lbs.Set(field, iter.ReadString())
+			// append to the buffer of labels
+			u.lbsBuffer = append(u.lbsBuffer, field, iter.ReadString())
 		default:
 			iter.Skip()
 		}
@@ -377,5 +383,11 @@ func (u *UnpackParser) unpack(it *jsoniter.Iterator, lbs *LabelsBuilder) ([]byte
 	if it.Error != nil && it.Error != io.EOF {
 		return nil, it.Error
 	}
+	// flush the buffer if we found a packed entry.
+	if isPacked {
+		for i := 0; i < len(u.lbsBuffer); i = i + 2 {
+			lbs.Set(u.lbsBuffer[i], u.lbsBuffer[i+1])
+		}
+	}
 	return entry, nil
 }
diff --git a/pkg/logql/log/parser_hints_test.go b/pkg/logql/log/parser_hints_test.go
index 988aa3b51524d..b32d9285206bd 100644
--- a/pkg/logql/log/parser_hints_test.go
+++ b/pkg/logql/log/parser_hints_test.go
@@ -29,12 +29,18 @@ var (
 	}
 }`)
 
+	packedLine = []byte(`{
+		"remote_user": "foo",
+		"upstream_addr": "10.0.0.1:80",
+		"protocol": "HTTP/2.0",
+		"cluster": "us-east-west",
+		"_entry":"foo"
+	}`)
+
 	logfmtLine = []byte(`ts=2021-02-02T14:35:05.983992774Z caller=spanlogger.go:79 org_id=3677 traceID=2e5c7234b8640997 Ingester.TotalReached=15 Ingester.TotalChunksMatched=0 Ingester.TotalBatches=0`)
 )
 
 func Test_ParserHints(t *testing.T) {
-	lbs := labels.Labels{{Name: "app", Value: "nginx"}, {Name: "cluster", Value: "us-central-west"}}
-
 	t.Parallel()
 	for _, tt := range []struct {
 		expr      string
@@ -185,14 +191,14 @@ func Test_ParserHints(t *testing.T) {
 		},
 		{
 			`sum by (cluster_extracted)(count_over_time({app="nginx"} | unpack | cluster_extracted="us-east-west" [1m]))`,
-			jsonLine,
+			packedLine,
 			true,
 			1.0,
 			`{cluster_extracted="us-east-west"}`,
 		},
 		{
 			`sum(rate({app="nginx"} | unpack | nonexistant_field="foo" [1m]))`,
-			jsonLine,
+			packedLine,
 			false,
 			0,
 			``,
@@ -200,7 +206,7 @@ func Test_ParserHints(t *testing.T) {
 	} {
 		tt := tt
 		t.Run(tt.expr, func(t *testing.T) {
-			t.Parallel()
+			lbs := labels.Labels{{Name: "app", Value: "nginx"}, {Name: "cluster", Value: "us-central-west"}}
 			expr, err := logql.ParseSampleExpr(tt.expr)
 			require.NoError(t, err)
 
diff --git a/pkg/logql/log/parser_test.go b/pkg/logql/log/parser_test.go
index 97a764d72a095..2b3dbcb782ba9 100644
--- a/pkg/logql/log/parser_test.go
+++ b/pkg/logql/log/parser_test.go
@@ -689,6 +689,19 @@ func Test_unpackParser_Parse(t *testing.T) {
 			},
 			[]byte(`some message`),
 		},
+		{
+			"should not change log and labels if no packed entry",
+			[]byte(`{"bar":1,"app":"foo","namespace":"prod","pod":{"uid":"1"}}`),
+			labels.Labels{
+				{Name: "app", Value: "bar"},
+				{Name: "cluster", Value: "us-central1"},
+			},
+			labels.Labels{
+				{Name: "app", Value: "bar"},
+				{Name: "cluster", Value: "us-central1"},
+			},
+			[]byte(`{"bar":1,"app":"foo","namespace":"prod","pod":{"uid":"1"}}`),
+		},
 	}
 	for _, tt := range tests {
 		j := NewUnpackParser()