diff --git a/src/class/cdc/cdc_device.c b/src/class/cdc/cdc_device.c
index 08f2af25..6c6318a3 100644
--- a/src/class/cdc/cdc_device.c
+++ b/src/class/cdc/cdc_device.c
@@ -230,6 +230,8 @@ void cdcd_init(void)
   for(uint8_t i=0; i<CFG_TUD_CDC; i++)
   {
     cdcd_interface_t* p_cdc = &_cdcd_itf[i];
+    
+    p_cdc->tx_ff.overwritable=false;
 
     p_cdc->wanted_char = (char) -1;