diff --git a/firmware/main.c b/firmware/main.c
index b60f45f..9b0ea1a 100755
--- a/firmware/main.c
+++ b/firmware/main.c
@@ -46,7 +46,8 @@ static uchar prog_blockflags;
 static uchar prog_pagecounter;
 
 
-ISR(SPI_STC_vect )
+
+ISR(SPI_STC_vect, ISR_NOBLOCK)
 {
     comBuffer[comStop] = SPDR;
     comStop ++;