diff --git a/sorting_searching/selection_sort/selection_sort_challenge.ipynb b/sorting_searching/selection_sort/selection_sort_challenge.ipynb
index f45e498..cee2ddd 100644
--- a/sorting_searching/selection_sort/selection_sort_challenge.ipynb
+++ b/sorting_searching/selection_sort/selection_sort_challenge.ipynb
@@ -44,6 +44,7 @@
    "source": [
     "## Test Cases\n",
     "\n",
+    "* None -> None\n",
     "* Empty input -> []\n",
     "* One element -> [element]\n",
     "* Two or more elements"