diff --git a/internal/decoder/string.go b/internal/decoder/string.go
index 9e8c737..5c2389e 100644
--- a/internal/decoder/string.go
+++ b/internal/decoder/string.go
@@ -239,7 +239,15 @@ func stringBytes(s *Stream) ([]byte, error) {
 			fallthrough
 		default:
 			// multi bytes character
-			r, size := utf8.DecodeRune(s.buf[cursor:])
+			if !utf8.FullRune(s.buf[cursor : len(s.buf)-1]) {
+				s.cursor = cursor
+				if s.read() {
+					_, cursor, p = s.stat()
+					continue
+				}
+				goto ERROR
+			}
+      r, size := utf8.DecodeRune(s.buf[cursor:])
 			if r == utf8.RuneError {
 				s.buf = append(append(append([]byte{}, s.buf[:cursor]...), runeErrBytes...), s.buf[cursor+1:]...)
 				cursor += runeErrBytesLen
diff --git a/stream_test.go b/stream_test.go
index 67c91ba..010b87e 100644
--- a/stream_test.go
+++ b/stream_test.go
@@ -14,6 +14,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"reflect"
+	"strconv"
 	"strings"
 	"testing"
 
@@ -502,6 +503,19 @@ func TestGzipStreaming(t *testing.T) {
 	}
 }
 
+func TestLongUTF8(t *testing.T) {
+	want := strings.Repeat("あ", 342)
+	r := strings.NewReader(strconv.Quote(want))
+
+	var got string
+	if err := json.NewDecoder(r).Decode(&got); err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+	if got != want {
+    t.Errorf("string %q; want = %q", got, want)
+	}
+}
+
 func TestIssue278(t *testing.T) {
 	a := `{"嗷嗷":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\u55f7"}`
 	r := strings.NewReader(a)