diff --git a/avr/main.c b/avr/main.c
index 814fbad..c430a24 100644
--- a/avr/main.c
+++ b/avr/main.c
@@ -66,11 +66,13 @@ ISR(TIMER0_COMPB_vect) {
  * SPI byte receipt interrupt vector
  */
 ISR(SPI_STC_vect) {
+    uint8_t value = SPDR;
+
     if (buffer.cur < buffer.read) {
         SPDR = buffer.data[buffer.cur++];
     }
 
-    uart_putchar(SPDR, NULL);
+    uart_putchar(value, NULL);
 }
 
 static void setup_clock_internal(tabby_clock_speed speed) {