diff --git a/ml3/spiral.py b/ml3/spiral.py
index 5292aea..e53b373 100644
--- a/ml3/spiral.py
+++ b/ml3/spiral.py
@@ -57,7 +57,7 @@ def plot_dataset(X,y):
     cm = plt.cm.RdBu
     plt.scatter(X[:,0], X[:,1], c=y, cmap=cm, lw=.5, s=10)
     
-def plot_decision_surface(X, y, classifier):
+def plot_decision_surface(X, y, classifier, h=0.02):
     h = .02
     cm = plt.cm.RdBu