diff --git a/Chapter2/macd.py b/Chapter2/macd.py
index cd29818..6936f5d 100644
--- a/Chapter2/macd.py
+++ b/Chapter2/macd.py
@@ -63,7 +63,7 @@
   if ema_macd == 0:
     ema_macd = macd
   else:
-    ema_macd = (macd - ema_macd) * K_slow + ema_macd # signal is EMA of MACD values
+    ema_macd = (macd - ema_macd) * K_macd + ema_macd # signal is EMA of MACD values
 
   macd_values.append(macd)
   macd_signal_values.append(ema_macd)