diff --git a/HowBadIsMyBatch.ipynb b/HowBadIsMyBatch.ipynb
index 87f429166d4..b5dabe28586 100644
--- a/HowBadIsMyBatch.ipynb
+++ b/HowBadIsMyBatch.ipynb
@@ -31,7 +31,7 @@
     "    return pd.merge(\n",
     "            vaersDescr['VAERSDATA'],\n",
     "            vaersDescr['VAERSVAX'],\n",
-    "            how='left',\n",
+    "            how = 'left',\n",
     "            left_index = True,\n",
     "            right_index = True,\n",
     "            validate = 'one_to_many')\n",