diff --git a/src/clockinator.S b/src/clockinator.S
index 35cb1c2..32f7750 100644
--- a/src/clockinator.S
+++ b/src/clockinator.S
@@ -8,6 +8,10 @@
 
 .global main
 
+isr_stop_blink:
+    rcall       stop_blink              ; Turn off PB0 when TCNT0=OCF0A
+    reti                                ; Exit interrupt
+
 main:
     ;cbi        DDRB,       PB1         ; Set EC11 clockwise on PB5 as input
     ;cbi        DDRB,       PB2         ; Set EC11 counter-clockwise on PB3 as input