diff --git a/2020-fall/seminars/sem01-pandas.ipynb b/2020-fall/seminars/sem01-pandas.ipynb
index 998a7093..bed6b060 100644
--- a/2020-fall/seminars/sem01-pandas.ipynb
+++ b/2020-fall/seminars/sem01-pandas.ipynb
@@ -1,5 +1,5 @@
 {
- "cells": [
+ "cells": [  
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -5671,7 +5671,7 @@
     "%%timeit\n",
     "\n",
     "for i in range(100):\n",
-    "    train1[i, 'distance_haversine'] = haversine_array(train1['pickup_latitude'].iloc[i], \n",
+    "    train1['distance_haversine'].iloc[i] = haversine_array(train1['pickup_latitude'].iloc[i], \n",
     "                                                      train1['pickup_longitude'].iloc[i], \n",
     "                                                      train1['dropoff_latitude'].iloc[i], \n",
     "                                                      train1['dropoff_longitude'].iloc[i])"