diff --git a/notebooks/unit4/unit4.ipynb b/notebooks/unit4/unit4.ipynb
index 884eddd7..f3389229 100644
--- a/notebooks/unit4/unit4.ipynb
+++ b/notebooks/unit4/unit4.ipynb
@@ -276,6 +276,8 @@
       "outputs": [],
       "source": [
         "import numpy as np\n",
+  	"if not hasattr(np, 'bool8'):\n",
+  	"    np.bool8 = np.bool_\n",
         "\n",
         "from collections import deque\n",
         "\n",