diff --git a/binary_clock.md b/binary_clock.md
index 92f5336..40b8e1a 100644
--- a/binary_clock.md
+++ b/binary_clock.md
@@ -57,6 +57,6 @@ sudo nano /etc/rc.local
 ```
 2. Add following before exit 0.
 ```
-/home/pi/binary-clock/clock.py &
+python3 /home/pi/binary-clock/clock.py &
 ```