diff --git a/mtkclient/Library/Connection/usblib.py b/mtkclient/Library/Connection/usblib.py
index 8917852b..6657a697 100755
--- a/mtkclient/Library/Connection/usblib.py
+++ b/mtkclient/Library/Connection/usblib.py
@@ -424,15 +424,16 @@ def usbread(self, resplen=None, maxtimeout=100):
         wMaxPacketSize = self.EP_IN.wMaxPacketSize
         extend = res.extend
         buffer = None
+        buflen=min(resplen,wMaxPacketSize)
         if self.fast:
-            buffer = self.buffer[:resplen]
+            buffer = self.buffer[:buflen]
         while len(res) < resplen:
             try:
                 if self.fast:
                     rlen = epr(buffer, timeout)
                     extend(buffer[:rlen])
                 else:
-                    extend(epr(resplen))
+                    extend(epr(buflen))
             except usb.core.USBError as e:
                 error = str(e.strerror)
                 if "timed out" in error:
@@ -454,7 +455,6 @@ def usbread(self, resplen=None, maxtimeout=100):
                 self.verify_data(res[:resplen], "RX:")
         return res[:resplen]
 
-
     def usbxmlread(self, maxtimeout=100):
         res = bytearray()
         timeout = 0