diff --git a/notebooks/tutorials/1_getting_started_lesson4/notebook.ipynb b/notebooks/tutorials/1_getting_started_lesson4/notebook.ipynb
index 421b8789..caf58462 100644
--- a/notebooks/tutorials/1_getting_started_lesson4/notebook.ipynb
+++ b/notebooks/tutorials/1_getting_started_lesson4/notebook.ipynb
@@ -374,11 +374,12 @@
     }
    ],
    "source": [
+    "import pandas as pd\n",
     "# Calculate factor-weighted long-short portfolio returns\n",
     "ls_factor_returns = al.performance.factor_returns(factor_data)\n",
     "\n",
     "# Plot cumulative returns for 5 day holding period\n",
-    "al.plotting.plot_cumulative_returns(ls_factor_returns['5D'], '5D');"
+    "al.plotting.plot_cumulative_returns(ls_factor_returns['5D'], '5D', freq=pd.tseries.offsets.BDay());"
    ]
   },
   {