diff --git a/src/encoding/json/bench_test.go b/src/encoding/json/bench_test.go
index 72cb349062c..c81ab8e9935 100644
--- a/src/encoding/json/bench_test.go
+++ b/src/encoding/json/bench_test.go
@@ -82,6 +82,7 @@ func codeInit() {
 }
 
 func BenchmarkCodeEncoder(b *testing.B) {
+	b.ReportAllocs()
 	if codeJSON == nil {
 		b.StopTimer()
 		codeInit()
@@ -99,6 +100,7 @@ func BenchmarkCodeEncoder(b *testing.B) {
 }
 
 func BenchmarkCodeMarshal(b *testing.B) {
+	b.ReportAllocs()
 	if codeJSON == nil {
 		b.StopTimer()
 		codeInit()
@@ -133,6 +135,7 @@ func benchMarshalBytes(n int) func(*testing.B) {
 }
 
 func BenchmarkMarshalBytes(b *testing.B) {
+	b.ReportAllocs()
 	// 32 fits within encodeState.scratch.
 	b.Run("32", benchMarshalBytes(32))
 	// 256 doesn't fit in encodeState.scratch, but is small enough to
@@ -143,6 +146,7 @@ func BenchmarkMarshalBytes(b *testing.B) {
 }
 
 func BenchmarkCodeDecoder(b *testing.B) {
+	b.ReportAllocs()
 	if codeJSON == nil {
 		b.StopTimer()
 		codeInit()
@@ -167,6 +171,7 @@ func BenchmarkCodeDecoder(b *testing.B) {
 }
 
 func BenchmarkUnicodeDecoder(b *testing.B) {
+	b.ReportAllocs()
 	j := []byte(`"\uD83D\uDE01"`)
 	b.SetBytes(int64(len(j)))
 	r := bytes.NewReader(j)
@@ -182,6 +187,7 @@ func BenchmarkUnicodeDecoder(b *testing.B) {
 }
 
 func BenchmarkDecoderStream(b *testing.B) {
+	b.ReportAllocs()
 	b.StopTimer()
 	var buf bytes.Buffer
 	dec := NewDecoder(&buf)
@@ -204,6 +210,7 @@ func BenchmarkDecoderStream(b *testing.B) {
 }
 
 func BenchmarkCodeUnmarshal(b *testing.B) {
+	b.ReportAllocs()
 	if codeJSON == nil {
 		b.StopTimer()
 		codeInit()
@@ -221,6 +228,7 @@ func BenchmarkCodeUnmarshal(b *testing.B) {
 }
 
 func BenchmarkCodeUnmarshalReuse(b *testing.B) {
+	b.ReportAllocs()
 	if codeJSON == nil {
 		b.StopTimer()
 		codeInit()
@@ -238,6 +246,7 @@ func BenchmarkCodeUnmarshalReuse(b *testing.B) {
 }
 
 func BenchmarkUnmarshalString(b *testing.B) {
+	b.ReportAllocs()
 	data := []byte(`"hello, world"`)
 	b.RunParallel(func(pb *testing.PB) {
 		var s string
@@ -250,6 +259,7 @@ func BenchmarkUnmarshalString(b *testing.B) {
 }
 
 func BenchmarkUnmarshalFloat64(b *testing.B) {
+	b.ReportAllocs()
 	data := []byte(`3.14`)
 	b.RunParallel(func(pb *testing.PB) {
 		var f float64
@@ -262,6 +272,7 @@ func BenchmarkUnmarshalFloat64(b *testing.B) {
 }
 
 func BenchmarkUnmarshalInt64(b *testing.B) {
+	b.ReportAllocs()
 	data := []byte(`3`)
 	b.RunParallel(func(pb *testing.PB) {
 		var x int64
@@ -300,6 +311,7 @@ func BenchmarkUnmapped(b *testing.B) {
 }
 
 func BenchmarkTypeFieldsCache(b *testing.B) {
+	b.ReportAllocs()
 	var maxTypes int = 1e6
 	if testenv.Builder() != "" {
 		maxTypes = 1e3 // restrict cache sizes on builders
diff --git a/src/encoding/json/decode.go b/src/encoding/json/decode.go
index 3900bcc165c..3f9fe1f5733 100644
--- a/src/encoding/json/decode.go
+++ b/src/encoding/json/decode.go
@@ -14,6 +14,7 @@ import (
 	"fmt"
 	"reflect"
 	"strconv"
+	"strings"
 	"unicode"
 	"unicode/utf16"
 	"unicode/utf8"
@@ -266,8 +267,8 @@ type decodeState struct {
 	opcode       int // last read result
 	scan         scanner
 	errorContext struct { // provides context for type errors
-		Struct reflect.Type
-		Field  string
+		Struct     reflect.Type
+		FieldStack []string
 	}
 	savedError            error
 	useNumber             bool
@@ -289,7 +290,9 @@ func (d *decodeState) init(data []byte) *decodeState {
 	d.off = 0
 	d.savedError = nil
 	d.errorContext.Struct = nil
-	d.errorContext.Field = ""
+
+	// Reuse the allocated space for the FieldStack slice.
+	d.errorContext.FieldStack = d.errorContext.FieldStack[:0]
 	return d
 }
 
@@ -303,11 +306,11 @@ func (d *decodeState) saveError(err error) {
 
 // addErrorContext returns a new error enhanced with information from d.errorContext
 func (d *decodeState) addErrorContext(err error) error {
-	if d.errorContext.Struct != nil || d.errorContext.Field != "" {
+	if d.errorContext.Struct != nil || len(d.errorContext.FieldStack) > 0 {
 		switch err := err.(type) {
 		case *UnmarshalTypeError:
 			err.Struct = d.errorContext.Struct.Name()
-			err.Field = d.errorContext.Field
+			err.Field = strings.Join(d.errorContext.FieldStack, ".")
 			return err
 		}
 	}
@@ -659,7 +662,7 @@ func (d *decodeState) object(v reflect.Value) error {
 	}
 
 	var mapElem reflect.Value
-	originalErrorContext := d.errorContext
+	origErrorContext := d.errorContext
 
 	for {
 		// Read opening " of string key or closing }.
@@ -730,11 +733,7 @@ func (d *decodeState) object(v reflect.Value) error {
 					}
 					subv = subv.Field(i)
 				}
-				if originalErrorContext.Field == "" {
-					d.errorContext.Field = f.name
-				} else {
-					d.errorContext.Field = originalErrorContext.Field + "." + f.name
-				}
+				d.errorContext.FieldStack = append(d.errorContext.FieldStack, f.name)
 				d.errorContext.Struct = t
 			} else if d.disallowUnknownFields {
 				d.saveError(fmt.Errorf("json: unknown field %q", key))
@@ -814,14 +813,17 @@ func (d *decodeState) object(v reflect.Value) error {
 		if d.opcode == scanSkipSpace {
 			d.scanWhile(scanSkipSpace)
 		}
+		// Reset errorContext to its original state.
+		// Keep the same underlying array for FieldStack, to reuse the
+		// space and avoid unnecessary allocs.
+		d.errorContext.FieldStack = d.errorContext.FieldStack[:len(origErrorContext.FieldStack)]
+		d.errorContext.Struct = origErrorContext.Struct
 		if d.opcode == scanEndObject {
 			break
 		}
 		if d.opcode != scanObjectValue {
 			panic(phasePanicMsg)
 		}
-
-		d.errorContext = originalErrorContext
 	}
 	return nil
 }
diff --git a/src/encoding/json/decode_test.go b/src/encoding/json/decode_test.go
index d99d65d7634..8da74fa3d35 100644
--- a/src/encoding/json/decode_test.go
+++ b/src/encoding/json/decode_test.go
@@ -50,7 +50,8 @@ type P struct {
 }
 
 type PP struct {
-	T T
+	T  T
+	Ts []T
 }
 
 type SS string
@@ -943,6 +944,17 @@ var unmarshalTests = []unmarshalTest{
 			Offset: 29,
 		},
 	},
+	{
+		in:  `{"Ts": [{"Y": 1}, {"Y": 2}, {"Y": "bad-type"}]}`,
+		ptr: new(PP),
+		err: &UnmarshalTypeError{
+			Value:  "string",
+			Struct: "T",
+			Field:  "Ts.Y",
+			Type:   reflect.TypeOf(int(0)),
+			Offset: 29,
+		},
+	},
 }
 
 func TestMarshal(t *testing.T) {