diff --git a/src/avrdude/ser_win32.c b/src/avrdude/ser_win32.c
index c62e83608..8efca0397 100644
--- a/src/avrdude/ser_win32.c
+++ b/src/avrdude/ser_win32.c
@@ -142,6 +142,7 @@ static BOOL serial_w32SetTimeOut(HANDLE hComPort, DWORD timeout) // in ms
 	// ctmo.ReadIntervalTimeout = timeout;
 	// ctmo.ReadTotalTimeoutMultiplier = timeout;
 	ctmo.ReadTotalTimeoutConstant = timeout;
+	ctmo.WriteTotalTimeoutConstant = timeout;
 
 	return SetCommTimeouts(hComPort, &ctmo);
 }