diff --git a/python/fbprophet/plot.py b/python/fbprophet/plot.py
index 5e5b407..3b7c10b 100644
--- a/python/fbprophet/plot.py
+++ b/python/fbprophet/plot.py
@@ -52,7 +52,7 @@ def plot(
     A matplotlib figure.
     """
     if ax is None:
-        fig = plt.figure(facecolor='w', figsize)
+        fig = plt.figure(facecolor='w', figsize=figsize)
         ax = fig.add_subplot(111)
     else:
         fig = ax.get_figure()