diff --git a/source/SerialComms.cpp b/source/SerialComms.cpp
index 36742e5e..a9e2fbf6 100644
--- a/source/SerialComms.cpp
+++ b/source/SerialComms.cpp
@@ -252,7 +252,7 @@ bool CSuperSerialCard::CheckComm()
 	{
 		_ASSERT(m_dwSerialPortItem < m_vecSerialPortsItems.size()-1);	// size()-1 is TCP item
 		TCHAR portname[SIZEOF_SERIALCHOICE_ITEM];
-		wsprintf(portname, TEXT("COM%u"), m_vecSerialPortsItems[m_dwSerialPortItem]);
+		wsprintf(portname, TEXT("\\\\.\\COM%u"), m_vecSerialPortsItems[m_dwSerialPortItem]);
 
 		m_hCommHandle = CreateFile(portname,
 								GENERIC_READ | GENERIC_WRITE,
@@ -1258,7 +1258,7 @@ void CSuperSerialCard::ScanCOMPorts()
 	for (UINT i=1; i<32; i++)	// Arbitrary upper limit
 	{
 		TCHAR portname[SIZEOF_SERIALCHOICE_ITEM];
-		wsprintf(portname, TEXT("COM%u"), i);
+		wsprintf(portname, TEXT("\\\\.\\COM%u"), i);
 
 		HANDLE hCommHandle = CreateFile(portname,
 								GENERIC_READ | GENERIC_WRITE,
diff --git a/source/SerialComms.h b/source/SerialComms.h
index 922cd02f..5925eb87 100644
--- a/source/SerialComms.h
+++ b/source/SerialComms.h
@@ -83,7 +83,7 @@ private:
 	//
 
 public:
-	static const UINT SIZEOF_SERIALCHOICE_ITEM = 8*sizeof(char);
+	static const UINT SIZEOF_SERIALCHOICE_ITEM = 12*sizeof(char);
 
 private:
 	std::string m_ayCurrentSerialPortName;