diff --git a/main.py b/main.py
index 995ae46..8f27bd0 100644
--- a/main.py
+++ b/main.py
@@ -11,7 +11,7 @@ def Coincounter(pin):
     global newCoin, pulses, timeAfter
     timeAfter = time.ticks_us()
     newCoin = True
-    pulses = pulses + 1
+    pulses += 1
 coinPin.irq(handler = Coincounter, trigger = Pin.IRQ_RISING)
 
 while True: