diff --git a/media/mtp/MtpDataPacket.cpp b/media/mtp/MtpDataPacket.cpp
index 930f0b0..c4f87a0 100644
--- a/media/mtp/MtpDataPacket.cpp
+++ b/media/mtp/MtpDataPacket.cpp
@@ -331,7 +331,7 @@
 
 void MtpDataPacket::putString(const uint16_t* string) {
     int count = 0;
-    for (int i = 0; i < 256; i++) {
+    for (int i = 0; i <= MTP_STRING_MAX_CHARACTER_NUMBER; i++) {
         if (string[i])
             count++;
         else