diff --git a/Ymodem.cpp b/Ymodem.cpp
index 742f51e..e771f0d 100644
--- a/Ymodem.cpp
+++ b/Ymodem.cpp
@@ -268,7 +268,7 @@ Ymodem::Code Ymodem::receivePacket()
       BOOST_LOG_TRIVIAL(debug) << "RX = " << int(rxBuffer[0]);
       if(rxBuffer[0] == CodeSoh)
       {
-        uint32_t len = read(&(rxBuffer[1]), YMODEM_PACKET_SIZE + YMODEM_PACKET_OVERHEAD - 1);
+        int32_t len = read(&(rxBuffer[1]), YMODEM_PACKET_SIZE + YMODEM_PACKET_OVERHEAD - 1);
 
         BOOST_LOG_TRIVIAL(debug) << "Len = " << len << " Start = " << rxBuffer[1];
 
@@ -286,7 +286,7 @@ Ymodem::Code Ymodem::receivePacket()
       }
       else if(rxBuffer[0] == CodeStx)
       {
-        uint32_t len = read(&(rxBuffer[1]), YMODEM_PACKET_1K_SIZE + YMODEM_PACKET_OVERHEAD - 1);
+        int32_t len = read(&(rxBuffer[1]), YMODEM_PACKET_1K_SIZE + YMODEM_PACKET_OVERHEAD - 1);
 
         if(len < (YMODEM_PACKET_1K_SIZE + YMODEM_PACKET_OVERHEAD - 1))
         {
@@ -315,7 +315,7 @@ Ymodem::Code Ymodem::receivePacket()
   {
     if(code == CodeSoh)
     {
-      uint32_t len = read(&(rxBuffer[rxLength]), YMODEM_PACKET_SIZE + YMODEM_PACKET_OVERHEAD - rxLength);
+      int32_t len = read(&(rxBuffer[rxLength]), YMODEM_PACKET_SIZE + YMODEM_PACKET_OVERHEAD - rxLength);
 
       if(len < (YMODEM_PACKET_SIZE + YMODEM_PACKET_OVERHEAD - rxLength))
       {
@@ -332,7 +332,7 @@ Ymodem::Code Ymodem::receivePacket()
     }
     else if(code == CodeStx)
     {
-      uint32_t len = read(&(rxBuffer[rxLength]), YMODEM_PACKET_1K_SIZE + YMODEM_PACKET_OVERHEAD - rxLength);
+      int32_t len = read(&(rxBuffer[rxLength]), YMODEM_PACKET_1K_SIZE + YMODEM_PACKET_OVERHEAD - rxLength);
 
       if(len < (YMODEM_PACKET_1K_SIZE + YMODEM_PACKET_OVERHEAD - rxLength))
       {