diff --git a/src/encoding/json/bench_test.go b/src/encoding/json/bench_test.go
index f7bcf8073c0..032114cac14 100644
--- a/src/encoding/json/bench_test.go
+++ b/src/encoding/json/bench_test.go
@@ -571,3 +571,14 @@ func BenchmarkNumberIsValidRegexp(b *testing.B) {
 		jsonNumberRegexp.MatchString(s)
 	}
 }
+
+func BenchmarkUnmarshalNumber(b *testing.B) {
+	b.ReportAllocs()
+	data := []byte(`"-61657.61667E+61673"`)
+	var number Number
+	for i := 0; i < b.N; i++ {
+		if err := Unmarshal(data, &number); err != nil {
+			b.Fatal("Unmarshal:", err)
+		}
+	}
+}
diff --git a/src/encoding/json/decode.go b/src/encoding/json/decode.go
index e1bc9753b11..ce566f79556 100644
--- a/src/encoding/json/decode.go
+++ b/src/encoding/json/decode.go
@@ -943,10 +943,11 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
 			}
 			v.SetBytes(b[:n])
 		case reflect.String:
-			if v.Type() == numberType && !isValidNumber(string(s)) {
+			t := string(s)
+			if v.Type() == numberType && !isValidNumber(t) {
 				return fmt.Errorf("json: invalid number literal, trying to unmarshal %q into Number", item)
 			}
-			v.SetString(string(s))
+			v.SetString(t)
 		case reflect.Interface:
 			if v.NumMethod() == 0 {
 				v.Set(reflect.ValueOf(string(s)))