diff --git a/SerialPort.cpp b/SerialPort.cpp
index 86259c3..529f5dd 100644
--- a/SerialPort.cpp
+++ b/SerialPort.cpp
@@ -413,7 +413,7 @@ void CSerialPort::process()
       if (m_ptr == 2U)
         m_len = m_buffer[1U];
 
-      if (m_ptr == 3U && m_len > 230U) {
+      if (m_ptr == 3U && m_len > 250U) {
         sendNAK(3U);
         m_ptr = 0U;
         m_len = 0U;
diff --git a/SerialPort.h b/SerialPort.h
index 5ad3881..d4981e7 100644
--- a/SerialPort.h
+++ b/SerialPort.h
@@ -60,7 +60,7 @@ private:
 #if defined(__MBED__)
   Serial  m_serial;
 #endif
-  uint8_t m_buffer[130U];
+  uint8_t m_buffer[250U];
   uint8_t m_ptr;
   uint8_t m_len;